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Filed pursuant to Rule 424(b)(5)
File No. 333-190931

PROSPECTUS SUPPLEMENT

(To prospectus dated September 24, 2013)

2,740,722 Shares in Primary Offering

499,263 Shares Pursuant to Distribution Reinvestment Plan

Senior Common Stock

We are offering 2,740,722 shares of our senior common stock, par value $0.001 per share, or Senior Common Stock, on a best efforts basis through our dealer manager, Gladstone Securities, LLC, or the Dealer Manager. We are also offering 499,263 shares of Senior Common Stock pursuant to our senior common distribution reinvestment plan to those stockholders who elect to participate in such distribution reinvestment plan, as further described in this prospectus supplement. We initially commenced the primary offering of 3,000,000 shares of Senior Common Stock and 500,000 shares of Senior Common Stock to be issued pursuant to the distribution reinvestment plan on March 28, 2011 pursuant to a prospectus supplement filed on March 28, 2011. As of the date of this prospectus supplement, 2,740,722 shares of Senior Common Stock to be issued pursuant to the primary offering and 499,263 shares of Senior Common Stock to be issued pursuant to the distribution reinvestment plan, remain unsold and un-issued. We reserve the right, to reallocate shares between the primary offering and the offering pursuant to the distribution reinvestment plan in our sole and absolute discretion.

Gladstone Securities, LLC, the Dealer Manager, is not required to sell any specific number or dollar amount of shares of Senior Common Stock but will use its “best efforts” to sell the shares offered by this prospectus supplement. The minimum permitted purchase of shares of Senior Common Stock is 200 shares having an aggregate minimum purchase price of $3,000. We reserve the right to waive the minimum purchase requirement in our sole and absolute discretion.

We hold two closings per month for our primary offering. The closing dates were randomly selected prior to the commencement of the primary offering, are not subject to change and will occur once between the 1st and 15th of each month and once between the 16th and last day of each month. We place your subscription payment in an account held by our escrow agent, BB&T Corporation, which funds will be held in trust for your benefit until the next closing date. On any such subsequent closing date, we will either accept or reject your subscription, and (i) if accepted, we will transfer your funds to our general account, and you will receive a confirmation of your subscription, or (ii) if rejected, we will return your funds, without interest, within 10 business days thereafter. Subscriptions are effective only upon our acceptance, and we reserve the right to reject any subscription either in whole or in part in our sole and absolute discretion.

The primary offering for our Senior Common Stock will terminate on the earlier of (i) March 28, 2015, unless earlier terminated or extended by our board of directors, or (ii) the date on which 2,740,722 shares of Senior Common Stock are sold hereunder. If we extend the primary offering period beyond March 28, 2015, we will update this prospectus supplement accordingly. We may extend the offering period for the 499,263 shares of Senior Common Stock being offered hereby under the distribution reinvestment plan beyond the termination of the primary offering and until we have sold all of the shares allocated to the distribution reinvestment plan through the reinvestment of distributions. We reserve the right, however, to terminate the primary offering and the offering pursuant to the distribution reinvestment plan at any time in our sole and absolute discretion.

Distributions paid on shares of Senior Common Stock (i) will be in an amount equal to $1.05 per share per annum, declared daily and paid at the rate of $0.0875 per share per month and (ii) must be paid before distributions are paid on shares of Listed Common Stock but after distributions are paid on shares of Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock.

There currently is no public market for shares of Senior Common Stock, and we do not expect to have the shares listed on any securities exchange or quoted on an automated quotation system. You may not be able to sell your shares of Senior Common Stock when you desire, or at all, and, if you are able to sell your shares, you may be forced to sell them at a substantial discount. Accordingly, if you invest in shares of Senior Common Stock, you will have limited liquidity. After the fifth anniversary from the date of issuance of the shares of Senior Common Stock, such shares, if not redeemed prior to that time, will be exchangeable by the holders thereof for shares of Listed Common Stock. Our Listed Common Stock is listed on the NASDAQ Global Select Market under the symbol “GOOD.”

We believe that we qualify, and have elected to be taxed as, a real estate investment trust, or REIT, for federal income tax purposes. To assist us in complying with certain federal income tax requirements applicable to REITs, our charter contains certain restrictions relating to the ownership and transfer of our capital stock, including an ownership limit of 9.8% on our outstanding capital stock by any person (which includes Listed Common Stock, Senior Common Stock and Preferred Stock). See “Certain Provisions of Maryland Law and of Our Charter And Bylaws — Restrictions on Ownership and Transfer” in the accompanying prospectus.

An investment in shares of Senior Common Stock involves substantial risks. See “Risk Factors” beginning on page S-29 of this prospectus supplement and in our most recent Annual Report on Form 10-K, our Quarterly Reports on Form 10-Q and other information that we file from time to time with the Securities and Exchange Commission which are incorporated by reference into this prospectus supplement and the accompanying prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

GLADSTONE SECURITIES, LLC

The date of this prospectus supplement is September 24, 2013

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Prospectus Supplement

Accompanying Prospectus

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You should rely only upon the information that is contained or incorporated by reference into this prospectus supplement, the accompanying prospectus and any applicable free writing prospectus that is required to be filed with the Securities and Exchange Commission, or SEC, in making a decision about whether to invest in our Senior Common Stock. We have not, and the Dealer Manager has not, authorized any other person to provide you with different or additional information. If anyone provides you with different or additional information, you should not rely upon it. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, any applicable free writing prospectus and the documents incorporated by reference herein or therein are accurate only as of the respective dates of such documents or such other dates as may be specified in these documents. Our business, financial condition, liquidity, results of operations, funds from operations and prospects may have changed since those dates.

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ABOUT THIS PROSPECTUS SUPPLEMENT

This document is presented in two parts. The first part is comprised of this prospectus supplement, which describes the specific terms of this offering and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference. The second part, the accompanying prospectus, contains a more detailed description of the shares of Senior Common Stock and provides more general information, some of which does not apply to this offering. To the extent that the information contained in this prospectus supplement differs or varies from the information contained in the accompanying prospectus or in the documents incorporated by reference herein or therein and previously filed with the SEC, the information in this prospectus supplement will supersede such information. In addition, the information that we file subsequently with the SEC prior to the completion of this offering will automatically update and supersede the information in this prospectus supplement.

This prospectus supplement is part of a registration statement that we have filed with the SEC using a continuing offering process. This prospectus supplement does not contain all of the information that we have included in the registration statement and in the accompanying exhibits and schedules thereto in accordance with the rules and regulations of the SEC, and we refer you to the omitted information. It is important for you to read and consider all of the information contained in this prospectus supplement and the accompanying prospectus in making your investment decision. You should also read and consider the additional information incorporated by reference into this prospectus supplement and the accompanying prospectus. See “Where You Can Find More Information” in this prospectus supplement.

Unless the context otherwise requires or indicates, all references in this prospectus supplement to (i) “we,” “our,” “us” and the “Company” mean Gladstone Commercial Corporation, a Maryland corporation, and its consolidated subsidiaries; (ii) “Board” mean the Company’s board of directors; (iii) “Operating Partnership” mean Gladstone Commercial Limited Partnership, a subsidiary of the Company and a Delaware limited partnership; (iv) “Adviser” mean Gladstone Management Corporation, a Delaware corporation and our external adviser; (v) “Administrator” mean Gladstone Administration, LLC, a Delaware limited liability company and our external administrator; (vi) “Dealer Manager” mean Gladstone Securities, LLC, a Connecticut limited liability company and the dealer manager for this offering; (vii) “Listed Common Stock” mean our common stock, par value $0.001 per share, which is listed on the NASDAQ Global Select Market under the symbol “GOOD;” (viii) “Senior Common Stock” mean our senior common stock, par value $0.001 per share; (ix) “Series A Preferred Stock” mean our 7.75% Series A Cumulative Redeemable Preferred Stock, par value $0.001 per share, which is listed on the NASDAQ Global Select Market under the symbol “GOODP;” (x) “Series B Preferred Stock” mean our 7.50% Series B Cumulative Redeemable Preferred Stock, par value $0.001 per share, which is listed on the NASDAQ Global Select Market under the symbol “GOODO;” and (xi) “Series C Preferred Stock” mean our 7.125% Series C Cumulative Term Preferred Stock, par value $0.001 per share, which is listed on the NASDAQ Global Select Market under the symbol “GOODN.” Unless the context indicates otherwise, we collectively refer to our Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock as our “Preferred Stock.”

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FORWARD-LOOKING STATEMENTS

This prospectus supplement and the accompanying prospectus, including the documents incorporated by reference into this prospectus supplement and the accompanying prospectus, contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. Also, documents we subsequently file with the SEC and incorporate by reference may contain forward-looking statements. Forward-looking statements provide our current expectations or forecasts of future events and are not statements of historical fact. These forward-looking statements include information about possible or assumed future events, including, among other things, discussion and analysis of our future financial condition, results of operations and funds from operations, or FFO, our strategic plans and objectives, cost management, occupancy and leasing rates and trends, liquidity and ability to refinance our indebtedness as it matures, anticipated capital expenditures (and access to capital) required to complete projects, amounts of anticipated cash distributions to our stockholders in the future and other matters. Words such as “anticipates,” “expects,” “intends,” “plans,” “believes,” “seeks,” “estimates” and variations of these words and similar expressions are intended to identify forward-looking statements. These statements are not guarantees of future performance and are subject to risks, uncertainties and other factors, some of which are beyond our control, are difficult to predict and/or could cause actual results to differ materially from those expressed or forecasted in the forward-looking statements. Statements regarding the following subjects, among others, are forward-looking by their nature:

Forward-looking statements involve inherent uncertainty and may ultimately prove to be incorrect. You are cautioned to not place undue reliance on forward-looking statements. Except as otherwise may be required by law, we undertake no obligation to update or revise forward-looking statements to reflect changed assumptions, the occurrence of unanticipated events or actual operating results. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of various factors, including, but not limited to:

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This list of risks and uncertainties, however, is only a summary of some of the most important factors to us and is not intended to be exhaustive. You should carefully review the risks and information contained, or incorporated by reference, in this prospectus supplement and the accompanying prospectus, including, without limitation, the “Risk Factors” incorporated by reference herein from our most recent Annual Report on Form 10-K, our Quarterly Reports on Form 10-Q and other reports and information that we file with the SEC. New factors may also emerge from time to time that could materially and adversely affect us.

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RISK FACTORS

An investment in shares of Senior Common Stock involves substantial risks. In consultation with your financial and legal advisers, you should carefully consider, among other matters, the factors set forth below as well as in our most recent Annual Report on Form 10-K, our Quarterly Reports on Form 10-Q and other information that we file from time to time with the SEC which are incorporated by reference into this prospectus supplement and the accompanying prospectus before deciding whether an investment in shares of Senior Common Stock is suitable for you. If any of the risks contained in or incorporated by reference into this prospectus supplement or the accompanying prospectus develop into actual events, our business, financial condition, liquidity, results of operations, FFO and prospects could be materially and adversely affected, the market price of our securities could decline and you may lose all or part of your investment.

Risks Related to our Adviser

We may have conflicts of interest with our Adviser and other affiliates.

Our Adviser manages our business and locates, evaluates, recommends and negotiates the acquisition of our real estate investments. At the same time, our advisory agreement permits our Adviser to conduct other commercial activities and provide management and advisory services to other entities, including, but not limited to, Gladstone Capital Corporation, or Gladstone Capital, Gladstone Investment Corporation, or Gladstone Investment, and Gladstone Land Corporation, or Gladstone Land. Moreover, with the exception of our chief financial officer and treasurer, and president, all of our officers and directors are also officers and directors of Gladstone Capital and Gladstone Investment, which actively make loans to and invest in small and medium-sized companies. In addition, with the exception of our president, all of our officers and eight of our nine directors are also officers and directors of Gladstone Land. Furthermore, Gladstone Securities, LLC, our Dealer Manager in our Senior Common Stock Offering and non-exclusive agent to assist us with arranging mortgage financing, pursuant to a Mortgage Financing Arrangement Agreement, effective June 18, 2013, is owned by David Gladstone, our chairman and chief executive officer. Mr. Jack Dellafiora, our chief compliance officer, and Mr. Michael LiCalsi, our internal counsel and secretary, who also serves as the president of our affiliated Administrator, serve on the Board of Managers of Gladstone Securities. As a result of the foregoing relationships, we may from time to time have conflicts of interest with our Adviser in its management of our business and with Gladstone Capital, Gladstone Investment and Gladstone Land, which may arise primarily from the involvement of our Adviser, Gladstone Capital, Gladstone Investment, Gladstone Land and their affiliates in other activities that may conflict with our business and we may also have conflicts of interest with Gladstone Securities, which may arise primarily due to the contractual agreements to which we are a party.

Examples of these potential conflicts include:

These and other conflicts of interest between us and our Adviser and other affiliates could have a material adverse effect on the operation of our business and the selection or management of our real estate investments.

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Risks Related to this Offering

There is no public market for shares of Senior Common Stock.

There is no established public trading market for shares of Senior Common Stock, and we currently have no plans to list these shares on a national securities exchange or to include these shares for quotation on any national securities market. Additionally, our charter contains restrictions on the ownership and transfer of shares of our capital stock, and these restrictions may inhibit your ability to sell your shares of Senior Common Stock promptly, or at all. If you are able to sell your shares, you may only be able to sell them at a substantial discount from the price which you paid for them. Therefore, you should purchase shares of Senior Common Stock only as a long-term investment. After five years from the date of issuance, shares of Senior Common Stock will be exchangeable at your option for shares of Listed Common Stock, which are currently traded on the NASDAQ Global Select Market under the symbol “GOOD.”

We would be required to terminate this offering if Listed Common Stock is no longer listed on the NASDAQ Global Select Market or another national securities exchange.

Senior Common Stock is a “covered security” and is therefore not subject to registration in the various states due to its seniority to Listed Common Stock, which is listed on the NASDAQ Global Select Market under the symbol “GOOD.” In the event that Listed Common Stock is no longer listed on the NASDAQ Global Select Market or another national securities exchange, we would be required to register the offering in any state in which we subsequently offered shares of Senior Common Stock. Such deregistration from the NASDAQ Global Select Market (i) would require the termination of this offering, (ii) could result in our raising gross proceeds in an amount that is substantially less than if we sold 2,740,722 shares of Senior Common Stock, and, consequently, (iii) would reduce our ability to purchase additional properties and limit the further diversification of our portfolio.

Our Dealer Manager is one of our affiliates, and, therefore, an investor in shares of Senior Common Stock would not have the benefit of an independent underwriter who has performed an independent due diligence review.

Our Dealer Manager is one of our affiliates. Because our Dealer Manager is an affiliate of ours, its due diligence review and investigation of us and this prospectus supplement cannot be considered to be an independent review. Therefore, although certain participating broker-dealers may elect to conduct or obtain an independent due diligence review of us prior to offering shares of Senior Common Stock, you may not have the benefit of an independent review and investigation of us and this offering of the type normally performed by an unaffiliated, independent underwriter in a public securities offering.

Your ability to redeem shares of Senior Common Stock pursuant to our share redemption program, with certain exceptions, is limited to the proceeds generated by our distribution reinvestment plan, and the share redemption program may be amended, suspended or terminated by our Board at any time without stockholder approval.

Our share redemption program is designed to provide holders of Senior Common Stock with limited interim liquidity by providing them with a limited opportunity to have their shares redeemed after they have held them for a period of one year. However, holders should understand that our share redemption program is limited to the amount of funds generated by our distribution reinvestment plan and is subject to certain other restrictions. The redemption price for shares of Senior Common Stock will be $13.80 per share. However, our Board may limit, suspend or terminate our share redemption program upon 30 days’ notice without stockholder approval. In addition, we will have no obligation to redeem shares if the redemption would violate the restrictions on distributions under Maryland law, which prohibits distributions that would cause a corporation to fail to meet statutory tests of solvency, or if our Board determines that such redemption could prevent us from qualifying as a

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REIT for federal income tax purposes. For more information on our share redemption program, including certain exceptions for the foregoing limitations for Special Redemptions (as defined therein), see “Share Redemption Program” in this prospectus supplement.

We will be able to call your shares of Senior Common Stock for redemption under certain circumstances without your consent.

We will have the ability to call the outstanding shares of Senior Common Stock after the fifth anniversary of the completion of this offering and at any time under certain circumstances relating to maintaining our ability to qualify as a REIT. At any such time, we will have the right to redeem, at our option, the outstanding shares of Senior Common Stock, in whole or in part, at a redemption price of $15.30 per share, plus any accrued and unpaid distributions.

If Listed Common Stock fails to meet all applicable listing requirements, it could be delisted from the NASDAQ Global Select Market, which could adversely affect the market price and liquidity of Listed Common Stock and Senior Common Stock and harm our financial condition and business.

Listed Common Stock currently is listed and traded on the NASDAQ Global Select Market under the symbol “GOOD.” If we fail to meet any of the continued listing standards of the NASDAQ Global Select Market, Listed Common Stock could be delisted from the exchange. The NASDAQ Global Select Market will consider the removal of a listed security on the exchange when, in its opinion, (i) the financial condition or operating results of an issuer appear to be unsatisfactory, (ii) it appears that the extent of public distribution or the aggregate market value of the security has become so reduced as to make further dealings on the NASDAQ Global Select Market inadvisable, (iii) the issuer has sold or otherwise disposed of its principal operating assets or has ceased to be an operating company, (iv) the issuer has failed to comply with its listing agreements with the NASDAQ Global Select Market or (v) any other event occurs or any condition exists which makes further dealings on the NASDAQ Global Select Market unwarranted.

If Listed Common Stock were to be delisted from the NASDAQ Global Select Market, it could be traded in the over-the-counter market or on an automated quotation system, such as the OTC Bulletin Board or the Pink Sheets. Any delisting could adversely affect the market price and the liquidity of Listed Common Stock and Senior Common Stock and negatively impact our financial condition and business.

We established the offering price of shares of Senior Common Stock on an arbitrary basis, and, as a result, the actual value of your investment may be substantially less than what you pay.

Our Board has arbitrarily determined the selling price of the shares of Senior Common Stock, and such price bears no relationship to our book or asset values, our projections of book or asset values or any other established criteria for valuing issued or outstanding shares. Because the offering price is not based upon any independent valuation, the offering price may not be indicative of the proceeds that you would receive upon liquidation.

The calculation of the Exchange Ratio could result in a deterrent to your exchanging shares of Senior Common Stock for shares of Listed Common Stock if shares of Listed Common Stock are trading at lower levels at the time that you desire to exchange your shares.

There is no prohibition on your ability to exchange your shares of Senior Common Stock for shares of Listed Common Stock after you have held them for five years. The Exchange Ratio, however, will be calculated by dividing $15.00 by the greatest of (i) the Closing Trading Price of Listed Common Stock on the date on which such shares of Senior Common Stock were originally issued, (ii) the Book Value Per Share of Listed Common Stock as determined as of the date on which such shares of Senior Common Stock were originally issued, or (iii) $13.68. If the trading price of shares of Listed Common Stock on the date of your exchange is less than the conversion price of your shares of Senior Common Stock at the time you propose to exchange your shares of

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Senior Common Stock for shares of Listed Common Stock, you would receive shares of Listed Common Stock with an aggregate fair market value that is less than the price you paid to purchase the shares of Senior Common Stock being exchanged. In such a situation, if you decided to exchange your shares of Senior Common Stock for shares of Listed Common Stock at such time and immediately liquidate your investment by selling your shares of Listed Common Stock, you would likely recognize a loss on your investment.

For example, the Closing Trading Price and the Book Value Per Share of the Listed Common Stock as of June 30, 2013 were $18.64 and $8.04, respectively. If you purchased shares of Senior Common Stock on June 30, 2013, the Exchange Ratio for the shares of Senior Common Stock that you purchased would be $15.00 divided by the greatest of $18.64, $8.04 or $13.68 per share. In this example, you would receive 0.80472 shares of Listed Common Stock for each share of Senior Common Stock ($15.00 divided by $18.64) upon electing to exchange your shares (at least five years after their issuance).

If you do not agree with the decisions of our Board, then you will not be able to influence changes in our policies and operations because holders of shares of Senior Common Stock will generally have no voting rights.

Our Board determines our major policies, including our policies regarding investments, financing, growth, REIT qualification and distributions. Because holders of shares of Senior Common Stock will have no voting rights (other than the right to consent to an amendment to our charter materially and adversely affecting the rights and preferences of shares of Senior Common Stock), you will have virtually no ability to change our policies and operations.

If you fail to meet the fiduciary and other standards under ERISA or the Code as a result of an investment in shares of Senior Common Stock, you could be subject to criminal and civil penalties.

There are special considerations that apply to employee benefit plans subject to ERISA (such as profit sharing, section 401(k) or pension plans) and other retirement plans or accounts subject to Section 4975 of the Code (such as an IRA) that invest in shares of Senior Common Stock. If you invest the assets of such a plan or account in shares of Senior Common Stock, you should satisfy yourself that, among other things:

Failure to satisfy the fiduciary standards of conduct and other applicable requirements of ERISA and the Code may result in the imposition of civil and criminal penalties and could subject the fiduciary to equitable remedies. In addition, if an investment in shares of Senior Common Stock constitutes a prohibited transaction under ERISA or the Code, the fiduciary that authorized or directed the investment may be subject to the imposition of excise taxes with respect to the amount invested.

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If our assets are deemed to be ERISA plan assets, we and our Adviser may be exposed to liabilities under Title 1 of ERISA and the Code.

In certain circumstances where an ERISA plan holds an interest in an entity, both the equity interest and an undivided interest in the underlying assets of the entire entity are deemed to be ERISA plan assets unless an exception applies. Under those circumstances, any person that exercises authority or control with respect to the management or disposition of the assets is an ERISA plan fiduciary, and the obligations and other responsibilities of plan sponsors, plan fiduciaries and plan administrators, and of parties in interest and disqualified persons, under Title I of ERISA and Section 4975 of the Code, as applicable, may apply. There may be liability under these and other provisions of ERISA and the Code. If our Adviser or we are exposed to liability under ERISA or the Code, our performance and results of operations could be adversely affected. Prior to making an investment in shares of Senior Common Stock, you should consult with your legal and other advisers concerning the impact of ERISA and the Code on your investment and our performance.

We may be unable to invest a significant portion of the net proceeds of this offering on acceptable terms.

Delays in investing the net proceeds of this offering may impair our performance. We cannot assure you that we will be able to identify properties that meet our investment objectives or that any investment we make will produce a positive return. We may be unable to invest the net proceeds of this offering on acceptable terms within the time period that we anticipate or at all, which could adversely affect our financial condition and operating results.

Our ability to pay dividends is limited by the requirements of Maryland law.

Our ability to pay dividends on our capital stock is limited by the laws of Maryland. Under applicable Maryland law, a Maryland corporation generally may not make a distribution if, after giving effect to the distribution, the corporation would not be able to pay its debts as the debts become due in the usual course of business or the corporation’s total assets would be less than the sum of its total liabilities plus, unless the corporation’s charter permits otherwise, the amount that would be needed, if the corporation were dissolved at the time of the distribution, to satisfy the preferential rights upon dissolution of stockholders whose preferential rights are superior to those receiving the distribution. Accordingly, we generally may not make a distribution on our capital stock if, after giving effect to the distribution, we would not be able to pay our debts as they become due in the usual course of business or our total assets would be less than the sum of our total liabilities plus, unless the terms of such class or series provide otherwise, the amount that would be needed to satisfy the preferential rights upon dissolution of the holders of shares of any class or series of preferred stock then outstanding, if any, with preferences upon dissolution senior to those of the Senior Common Stock.

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ESTIMATED USE OF PROCEEDS

We initially commenced the primary offering of 3,000,000 shares of Senior Common Stock and 500,000 shares of Senior Common Stock to be issued pursuant to the distribution reinvestment plan on March 28, 2011 pursuant to a prospectus supplement filed on March 28, 2011. As of the date of this prospectus supplement, we have sold 259,278 shares of Senior Common Stock in the primary offering, generating net proceeds of approximately $3.4 million, after deducting selling commissions and dealer manager fees and other offering expenses. As of the date of this prospectus supplement, 2,740,722 shares of Senior Common Stock and 499,263 shares of Senior Common Stock remain available for issuance in connection with the primary offering and the distribution reinvestment plan, respectively. The following table (i) estimates the use of the proceeds raised in this offering by assuming that we will sell all of the remaining 2,740,722 shares of Senior Common Stock in our primary offering at a price to the public of $15.00 per share and (ii) assumes that we do not sell any shares of Senior Common Stock pursuant to our distribution reinvestment plan. We anticipate that all or substantially all of the proceeds from the sale of shares of Senior Common Stock pursuant to our distribution reinvestment plan will be used to fund repurchases of shares of Senior Common Stock under our share redemption program rather than real estate-related investments.

The amounts in this table assume that the full selling commissions and Dealer Manager fees are paid on all shares of Senior Common Stock offered to the public on a best efforts basis. We have not given effect to any special sales or volume discounts that could reduce the sales commissions or Dealer Manager fees for sales pursuant to our primary offering. Reduction in these fees will be accompanied by a corresponding reduction in the per share purchase price but will not materially affect the amounts available to us for investment. See “Plan of Distribution” in this prospectus supplement.

Certain of the figures set forth below represent management’s best estimate as such figures cannot be precisely calculated at this time. If we were to sell 2,740,722 shares of Senior Common Stock in our primary offering at a price to the public of $15.00 per share, we estimate that approximately 89% of the proceeds that you invest will be available for one or more of the following purposes:

The remaining 11% of the proceeds will be used to pay sales commissions, Dealer Manager fees and other offering expenses.

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There can be no assurance we will be able to sell all of the shares of Senior Common Stock that we are registering. If we sell only a portion of the shares that we are registering, we may be unable to achieve our investment objectives.

Pending application of any portion of the net proceeds as described above, we may invest it in interest-bearing accounts and short-term, interest-bearing securities as is consistent with our intention to maintain our qualification as a REIT for federal income tax purposes. Such investments may include, for example, obligations of the Government National Mortgage Association, other government and governmental agency securities, certificates of deposit and interest-bearing bank deposits or other authorized investments that we determine.

Distributions

In order to qualify as a REIT, we are required to make certain distributions to our stockholders. The amount of these distributions must equal at least the sum of (i) 90% of our “REIT taxable income” (computed without regard to the distributions paid deduction and net capital gain) and (ii) 90% of the net income (after tax), if any, from foreclosure property, less the sum of certain non-cash items. Our Board may authorize distributions in excess of those required for us to maintain our REIT status depending upon our financial condition and such other factors as our Board deems relevant from time to time. Because we own and depreciate real estate, the depreciation expense reduces our net income. As a result, we have in the past elected to pay distributions to our Listed Common Stockholders in excess of our net income.

For federal income tax purposes, our distributions generally consist of ordinary income, capital gain, nontaxable return of capital or a combination thereof. Distributions that exceed our current and accumulated earnings and profits (calculated for federal income tax purposes) constitute a return of capital, which reduces the stockholder’s basis in its shares of our stock and will not be taxable to the stockholder to the extent of the stockholder’s basis in its shares of our stock. To the extent that a distribution exceeds the stockholder’s share of current and accumulated earnings and profits and the stockholder’s basis in its shares of our stock, that distribution will be treated as a capital gain from the sale or exchange of that stockholder’s shares of our stock. There were no capital gains during the last three years.

The characterization of distributions during each of the years ending 2010, 2011 and 2012 is reflected in the table below:

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The table above will be updated for the year ended December 31, 2013 in our Annual Report on Form 10-K that is expected to be filed with the SEC in February 2014.

Distributions paid in respect of shares of Senior Common Stock must be paid before distributions are paid on shares of Listed Common Stock but after distributions are paid on shares of Preferred Stock. For the year ended December 31, 2012, the distributions paid in respect of shares of Listed Common Stock were $16.4 million, and the total FFO available to holders of shares of Listed Common Stock was approximately $16.4 million. This means that $16.4 million would have been available to pay to holders of shares of Senior Common Stock before any payment to the holders of shares of Listed Common Stock. This further means that, if all of the shares of Senior Common Stock contemplated to be sold in this offering had been outstanding at the end of December 31, 2012, the indicated distribution of $2.9 million in respect of shares of Senior Common Stock would have been covered in payment by 5.6 times. However, we cannot guarantee that past results will be replicated in future years.

Every year, we notify stockholders of the taxability of distributions paid during the preceding year. See “Material U.S. Federal Income Tax Considerations” in the accompanying prospectus.

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DISTRIBUTION REINVESTMENT PLAN

Our distribution reinvestment plan allows you to have distributions that would otherwise be distributable to you invested in additional shares of Senior Common Stock. We are offering 499,263 shares of Senior Common Stock under our distribution reinvestment plan which are not included in the 2,740,722 shares being sold in the primary offering. As noted above, the primary offering will terminate at the end of the offering period. However, we may extend the offering period for our distribution reinvestment plan beyond the termination of the primary offering and until we have sold all of the shares allocated to the distribution reinvestment plan through the reinvestment of distributions. The following discussion summarizes the principal terms of our distribution reinvestment plan, a copy of which is appended to this prospectus supplement as Appendix B.

Participation in our distribution reinvestment plan is limited to investors who have purchased shares of Senior Common Stock in the primary offering. We may elect to deny your participation in our distribution reinvestment plan if you reside in a jurisdiction or foreign country where, in our sole and absolute discretion, the burden or expense of compliance with applicable securities laws makes your participation impracticable or inadvisable or if your participation in the distribution reinvestment plan could cause 25% or more of any class of our equity securities to be held by “benefit plan investors.” See “ERISA Considerations — Exception for Insignificant Participation by Benefit Plan Investors.” Assuming that you are eligible, you may elect to participate in our distribution reinvestment plan by completing the relevant portion of the Subscription Agreement or other approved enrollment form available from the Dealer Manager or a participating broker-dealer.

Your participation in our distribution reinvestment plan will begin with the next distribution made after receipt of your enrollment form. Once enrolled, you may continue to purchase shares of Senior Common Stock under our distribution reinvestment plan until we have terminated such plan. You can choose to have all or a portion of your distributions reinvested through our distribution reinvestment plan. You may also change the percentage of your distributions that will be reinvested at any time if you complete a new enrollment form or other form provided for that purpose. Any election to increase your level of participation must be made through your participating broker-dealer or, if you purchased shares of Senior Common Stock in this offering other than through a participating broker-dealer, through the Dealer Manager.

Shares of Senior Common Stock will be purchased under our distribution reinvestment plan on our distribution payment dates. The purchase of fractional shares is a permissible and likely result of the reinvestment of distributions under our distribution reinvestment plan.

During our primary offering, the purchase price per share of Senior Common Stock is $15.00. The offering price for shares purchased under our distribution reinvestment plan may increase after the closing of our primary offering. Fees are included in the price, and we will not charge you any other fees in connection with your purchase of shares under our distribution reinvestment plan. The price for shares purchased under our distribution reinvestment plan bears little relationship to, and will likely exceed, what you might receive for your shares if you tried to sell them or if we liquidated our portfolio. Purchases of shares of Senior Common Stock under our distribution reinvestment plan may effectively lower the total return on your investment with us. Our Board reserves the right to designate that certain cash or other distributions attributable to net sale proceeds will be excluded from distributions that may be reinvested in shares under our distribution reinvestment plan.

Within 90 days after the end of each calendar year, we provide investors with an individualized report regarding their respective investment, including the purchase dates, purchase price, number of shares owned, and the amount of distributions in the prior year.

We will not pay a commission in connection with your purchase of Senior Common Stock in our distribution reinvestment plan. No Dealer Manager fees or due diligence expense allowance will be paid in respect of shares of Senior Common Stock sold under the distribution reinvestment plan. We will not receive a fee for selling stock under our distribution reinvestment plan. See “Plan of Distribution” in this prospectus supplement.

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Shares of Senior Common Stock acquired through our distribution reinvestment plan, like all other shares of Senior Common Stock, will not have voting rights, except as set forth in “Description of Capital Stock — Common Stock — Senior Common Stock — Voting Rights” in the accompanying prospectus or as otherwise from time to time may required by law.

If you elect to participate in our distribution reinvestment plan and are subject to federal income taxation, you may incur a tax liability for distributions allocated to you even though you have elected not to receive the distributions in cash but rather to have the distributions withheld and reinvested pursuant to our distribution reinvestment plan.

Specifically, you will be treated as if you have received the distribution in cash and then applied such distribution to the purchase of additional shares of Senior Common Stock. You will be taxed on the amount of such distribution as a dividend to the extent such distribution is from current or accumulated earnings and profits, unless we have designated all or a portion of the distribution as a capital gain distribution. We will withhold 28% of the amount of distributions paid if you fail to furnish a valid taxpayer identification number, fail to properly report interest or distributions or fail to certify that you are not subject to withholding.

You may terminate your participation in our distribution reinvestment plan at any time by providing us with written notice. Any transfer of your shares of Senior Common Stock will effect a termination of the participation of those shares in our distribution reinvestment plan. Moreover, we will terminate your participation to the extent that a reinvestment of your distributions in shares of Senior Common Stock would cause you to exceed the ownership limitation contained in our charter. We will also terminate your participation to the extent that your continued participant could cause 25% or more of any class of our equity securities to be held by “benefit plan investors.” See “ERISA Considerations — Exception for Insignificant Participation by Benefit Plan Investors” in this prospectus supplement.

We may amend or terminate our distribution reinvestment plan in our sole and absolute discretion at any time upon ten days’ prior written notice to participants, but no such amendment will add compensation to the distribution reinvestment plan or remove the opportunity for you to terminate your participation in the distribution reinvestment plan, as specified above.

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SHARE REDEMPTION PROGRAM

Our Board has adopted a share redemption program that enables our stockholders to sell their shares of Senior Common Stock to us after they have held them for at least one year, subject to the conditions and limitations described below.

Senior Common Stock is currently not listed on a national securities exchange, or included for quotation on a national securities market, and we do not intend to seek to list Senior Common Stock. In order to provide stockholders with the benefit of interim liquidity, stockholders who have held their shares of Senior Common Stock for at least one year may present all or a portion consisting of at least 25% of their shares to us for redemption at any time in accordance with the procedures outlined below. At that time, we may, subject to the conditions and limitations described below, redeem the shares presented for redemption for cash to the extent that we have sufficient funds available to us to fund such redemption. The redemption price for shares of Senior Common Stock will be $13.80 per share. We will not pay to our Board, our Advisor or their affiliates any fees to complete any transactions under our share redemption program.

You generally must hold your shares of Senior Common Stock for one year before redeeming your shares under the share redemption program; however, we will waive the one-year holding period in the event of a redemption request upon the death, disability or bankruptcy of a stockholder, each a Special Redemption.

During any calendar year, we will not redeem in excess of 5% of the weighted average number of shares of Senior Common Stock outstanding during the prior calendar year. The cash available for redemption will be limited to the proceeds from the sale of shares of Senior Common Stock pursuant to our distribution reinvestment plan. Shares redeemed in a Special Redemption are not limited by foregoing restrictions and will be repurchased at a purchase price equal to the price actually paid for the shares.

We will redeem shares of Senior Common Stock on the last business day of the month following the end of each quarter. Requests for redemption would have to be received at or prior to the end of the quarter in order for us to repurchase the shares as of the end of the next month. You may withdraw your request to have your shares redeemed at any time prior to the last day of the applicable quarter.

If we cannot purchase all shares presented for redemption in any quarter, based upon insufficient cash available and the limit on the number of shares of Senior Common Stock that we may redeem during any calendar year, we would attempt to honor redemption requests on a pro rata basis. We would treat the unsatisfied portion of the redemption request as a request for redemption for the following quarter. At such time, you may then (i) withdraw your request for redemption at any time prior to the last day of the new quarter or (ii) ask that we honor your request at such time, if, any, as sufficient funds become available. Such pending requests will generally be honored on a pro rata basis. We will determine whether we have sufficient funds available as soon as practicable after the end of each quarter but, in any event, prior to the applicable payment date.

Our Board may choose to amend, suspend or terminate our share redemption program in its sole and absolute discretion upon 30 days’ notice at any time. Because the redemption of shares will be funded with the net proceeds that we receive from the sale of shares of Senior Common Stock under our distribution reinvestment plan, the discontinuance or termination of our distribution reinvestment plan will adversely affect our ability to redeem shares under our share redemption program. We would notify you of such developments (i) in our annual or quarterly reports filed with the SEC or (ii) by means of a separate mailing to you.

Our share redemption program is only intended to provide interim liquidity for stockholders. Shares of Senior Common Stock will not be eligible for redemption under our share redemption program commencing on the date such shares become exchangeable for shares of Listed Common Stock (i.e., five years after the issuance of such shares of Senior Common Stock).

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CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS

Advisory and Administration Agreements

Pursuant to the Advisory Agreement, our Adviser is responsible for our daily operations, record keeping and regulatory compliance functions. Specifically, these responsibilities include (i) identifying, evaluating, negotiating and consummating all investment transactions consistent with our investment objectives and criteria, (ii) providing us with all required records and reporting regularly to our Board concerning our Adviser’s efforts on our behalf, and (iii) maintaining our compliance with all regulatory requirements that are applicable to us. The Advisory Agreement provides for an annual base management fee equal to 2% of our total stockholders’ equity (including equity attributable to shares of Senior Common Stock) less the recorded value of any shares of preferred stock, and a performance-based incentive fee based upon our FFO, which rewards our Adviser if our quarterly FFO (before giving effect to any incentive fee) exceeds 1.75% (7% annualized) of our total stockholders’ equity (less the recorded value of any preferred stock). Our Adviser has the ability to issue a full or partial waiver of the incentive fee and may do so in order that we may maintain the current level of distributions to holders of our capital stock. For the years ended December 31, 2012, 2011 and 2010, an unconditional and irrevocable voluntary waiver was issued by our Adviser for approximately $2.2 million, $2.1 million and $0.2 million, respectively. For the six month period ended June 30, 2013, an unconditional and irrevocable voluntary waiver was issued by our Adviser for approximately $1.5 million. These waivers were applied through June 30, 2013, and any waived fees may not be recouped by our Adviser in the future.

Pursuant to the Administration Agreement, we pay separately for our allocable portion of our Administrator’s overhead expenses in performing its obligations to us, including, but not limited to, rent and our allocable portion of the salaries and benefits expenses attributable to our Administrator’s employees including our chief financial officer and treasurer, chief compliance officer, internal counsel and secretary and their respective staffs.

Messrs. Gladstone, Brubaker and Cutlip are all officers or directors, or both, of our Adviser. Messrs. Gladstone and Brubaker are also officers and directors of the Administrator. Mr. Gladstone is the sole stockholder of our Adviser and our Administrator. Although we believe that the terms of the Advisory Agreement and the Administration Agreement are no less favorable to us than those that could be obtained from unaffiliated third parties in arms’-length transactions, our Adviser, its officers and its directors have a material interest in the terms of these agreements.

As of June 30, 2013, we owed our Adviser approximately $0.8 million in fees pursuant to the Advisory and Administration Agreements.

Allocation of our Adviser’s Time

We will rely, in part, upon our Adviser to manage our day-to-day activities and to implement our investment strategy. Our Adviser and Administrator are currently the external investment adviser and administrator, respectively, for Gladstone Capital Corporation, or GLAD, a NASDAQ-listed business development company, or BDC, that primarily makes mezzanine and second lien loans to small businesses; Gladstone Investment Corporation, or GAIN, a NASDAQ-listed BDC active in buying small businesses; and Gladstone Land Corporation, or LAND, a NASDAQ-listed agricultural real estate company. As a result of these activities, our Adviser, its employees and certain of its affiliates will have conflicts of interest in allocating their time between us and other activities in which they are or may become involved.

Our Adviser and its employees will devote only as much of its time to our business as our Adviser and its employees, in their judgment, determine is reasonably required, which may be substantially less than their full time. Therefore, our Adviser, its personnel, and certain affiliates may experience conflicts of interest in allocating management time, services, and functions among us and any other business ventures in which they or any of their

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key personnel, as applicable, are or may become involved. This could result in actions that are more favorable to other affiliated entities than to us. However, our Adviser believes that it and its affiliates have sufficient personnel to discharge fully their responsibilities to all activities in which they are involved.

Affiliated Dealer Manager

We have engaged Gladstone Securities, LLC, which is owned by Mr. Gladstone, our chairman and chief executive officer, as our dealer manager and will pay fees to such entity pursuant to the dealer management agreement. Under the terms of the dealer manager agreement, the Dealer Manager is expected to act as our exclusive dealer manager until the end of the offering period or until the dealer manager agreement is terminated by us or them. Because the Dealer Manager is affiliated with us you will not have the benefit of an independent due diligence review and investigation of the type normally performed by an independent underwriter in connection with an underwritten offering of securities. See “Plan of Distribution” in this prospectus supplement.

We also entered into an agreement with Gladstone Securities, effective June 18, 2013, for it to act as our non-exclusive agent to assist us with arranging mortgage financing for properties we own. In connection with this engagement, Gladstone Securities may from time to time solicit the interest of various commercial real estate lenders or recommend to us third party lenders offering credit products or packages that are responsive to our needs. We will pay Gladstone Securities a financing fee, or the Financing Fee, in connection with the services it provides to us for securing mortgage financing on any of our properties. The amount of the Financing Fee, which is payable upon closing of the financing, will be based on a percentage of the amount of the mortgage ranging from 0.5% to a maximum of 1% of the mortgage obtained. The amount of the Financing Fee may be reduced or eliminated as determined by us and Gladstone Securities, after taking into consideration various factors, including, but not limited to, the involvement of any third party brokers and market conditions. No such fees were paid as of June 30, 2013. The agreement is scheduled to terminate on August 31, 2014 unless renewed or earlier terminated pursuant to the provisions contained therein.

Offering Expenses

Our Adviser will be responsible for any offering expenses that exceed $358,100 without recourse against or reimbursement by us.

Conflict of Interest Policy

We have adopted policies to reduce potential conflicts of interest. In addition, our directors are subject to certain provisions of Maryland law that are designed to minimize conflicts. Under our current conflict of interest policy, without the approval of a majority of our disinterested directors, we will not:

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Where allowed by applicable rules and regulations, from time to time, we may enter into transactions with our Adviser or one or more of its affiliates. A majority of our independent directors and a majority of our directors not otherwise interested in a transaction with our Adviser must approve all such transactions with our Adviser or its affiliates.

It is our current policy that we will not purchase any property from or co-invest with our Adviser, any of its affiliates or any business in which our Adviser or any of its subsidiaries have invested except that we may make leases to existing and prospective portfolio companies of entities advised by our Adviser, as long as the portfolio company is not controlled by that entity and the transaction is approved by both companies’ boards. If we decide to change this policy on co-investments with our Adviser or its affiliates, we will seek approval of this decision from our stockholders entitled to vote on this matter.

Indemnification

In our charter and bylaws, we have agreed to indemnify our directors and certain of our officers by providing, among other things, that we will indemnify such officer or director, under the circumstances and to the extent provided for therein, for expenses, damages, judgments, fines and settlements he or she may be required to pay in actions or proceedings, which he or she is or may be made a party by reason of his or her position as a director, officer or other agent of ours, and otherwise to the fullest extent permitted under Maryland law and our bylaws. Each of the Advisory and Administration Agreements provide that, absent willful misfeasance, bad faith or gross negligence in the performance of their duties or by reason of the reckless disregard of their duties and obligations, our Adviser, our Administrator and their respective officers, managers, agents, employees, controlling persons, members and any other person or entity affiliated with them are entitled to indemnification from us for any damages, liabilities, costs and expenses (including reasonable attorneys’ fees and amounts reasonably paid in settlement) arising from the rendering of our Adviser’s or our Administrator’s services under the current Advisory or Administration Agreements, respectively, or otherwise as an investment adviser of ours. Each of the Advisory and Administration Agreements provide that, absent willful misfeasance, bad faith or gross negligence in the performance of their duties or by reason of the reckless disregard of their duties and obligations, our Adviser, our Administrator and their respective officers, managers, agents, employees, controlling persons, members and any other person or entity affiliated with them are entitled to indemnification from us for any damages, liabilities, costs and expenses (including reasonable attorneys’ fees and amounts reasonably paid in settlement) arising from the rendition of services pursuant to the Advisory or Administration Agreements, respectively, or otherwise as an investment adviser of the Company.

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ADDITIONAL MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS

The following summary of additional material U.S. federal income tax considerations supplements the discussion set forth under the heading “Material U.S. Federal Income Tax Considerations” in the accompanying prospectus, is for general information purposes only and is not tax advice. This discussion does not address with all aspects of taxation that may be relevant to particular holders of our Senior Common Stock in light of their personal investment or tax circumstances.

We urge you to consult your own tax advisor regarding the specific tax consequences to you of the acquisition, ownership and disposition of our Senior Common Stock and of our election to be taxed as a REIT. Specifically, you should consult your own tax advisor regarding the federal, state, local, foreign and other tax consequences of such acquisition, ownership, disposition and election and regarding potential changes in applicable tax laws.

Taxation of Taxable U.S. Stockholders

Redemption or Repurchase of Senior Common Stock. A redemption or repurchase of our Senior Common Stock will be treated for federal income tax purposes as a distribution taxable as a dividend to the extent of our current and accumulated earnings and profits allocable to such Senior Common Stock unless the redemption or repurchase satisfies one of the exceptions set forth in the Code to such treatment and therefore is treated as a sale or exchange of such Senior Common Stock. The redemption or repurchase of our Senior Common Stock will be treated as a sale or exchange by a U.S. stockholder if it:

In determining whether any of these exceptions has been met, stock considered to be owned by the U.S. stockholder by reason of certain constructive ownership rules in the Code, as well as stock actually owned by the U.S. stockholder, generally must be taken into account. To the extent that one or more classes of our stock are widely held and publicly traded at any time that we repurchase our Senior Common Stock, such repurchase generally will be treated as a sale or exchange if it results in a proportionate reduction of a non-controlling U.S. stockholder’s right to participate in current earnings and accumulated surplus or to share in our net assets on liquidation. Because the determination as to whether any of the exceptions described above will be satisfied with respect to the U.S. stockholder depends upon the facts and circumstances at the time that the determination must be made, U.S. stockholders are advised to consult their tax advisors to determine such tax treatment.

If a redemption or repurchase of our Senior Common Stock is treated as a distribution taxable as a dividend for federal income tax purposes, the amount of the distribution will be measured by the amount of cash and the fair market value of any property received. In such case, a U.S. stockholder’s adjusted tax basis for federal income tax purposes in the redeemed or repurchased stock will be transferred to its remaining stock, if any. If a U.S. stockholder disposes of its entire interest in our stock as a result of such redemption or repurchase, such adjusted tax basis may, under certain circumstances, be transferred to a related person or it may be lost entirely.

If a redemption or repurchase of our Senior Common Stock is not treated as a distribution taxable as a dividend, it will be treated as a taxable sale or exchange in the manner described in the accompanying prospectus under “Material U.S. Federal Income Tax Considerations — Taxation of Taxable U.S. Stockholders — Distributions.”

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a redemption premium as a result of such rights and that any payments in excess of the issue price will be taxable to a holder of Senior Common Stock as described above. The IRS may take a contrary position from that described above, however, which could affect the timing and character of any income recognized by a U.S. stockholder in connection with the redemption or repurchase of such Senior Common Stock.

Conversion of Senior Common Stock into Common Stock. Except as provided below for fractional shares, a U.S. stockholder generally will not recognize gain or loss upon the conversion of our Senior Common Stock into our common stock, and the U.S. stockholder’s adjusted tax basis and holding period in our common stock received upon a conversion of our Senior Common Stock into our common stock generally will be the same as the U.S. stockholder’s adjusted tax basis and holding period in such Senior Common Stock (but the adjusted tax basis will be reduced by the portion of such adjusted tax basis allocated to any fractional share of Senior Common Stock exchanged for cash).

Cash received by a U.S. stockholder upon the conversion of our Senior Common Stock into our common stock in lieu of a fractional share of our common stock generally will be treated for federal income tax purposes as a payment in a taxable exchange for such fractional share, and such U.S. stockholder will recognize gain or loss in an amount equal to the difference between the amount of cash received and the adjusted tax basis allocable to the fractional share deemed exchanged. Any such gain or loss will be long-term capital gain or loss if the U.S. stockholder has held the converted Senior Common Stock for more than one year.

Taxation of Non-U.S. Stockholders

Conversion of Senior Common Stock into Common Stock. Except as provided below for fractional shares, a non-U.S. stockholder generally will not recognize gain or loss upon a conversion of our Senior Common Stock into our common stock, provided that such Senior Common Stock does not constitute a “United States real property interest,” or USRPI. Even if our Senior Common Stock does constitute a USRPI, provided that our common stock also constitutes a USRPI, a non-U.S. stockholder generally will not recognize gain or loss upon a conversion of our Senior Common Stock into our common stock. Except as provided below, a non-U.S. stockholder’s adjusted tax basis and holding period in the common stock received upon a conversion of our Senior Common Stock into our common stock will be the same as the non-U.S. stockholder’s adjusted tax basis and holding period in such Senior Common Stock (but the adjusted tax basis will be reduced by the portion of the non-U.S. stockholder’s adjusted tax basis allocated to any fractional share of Senior Common Stock exchanged for cash). Cash received in lieu of a fractional share of our common stock in connection with a conversion of our Senior Common Stock into our common stock generally will be treated as a payment in a taxable exchange for such fractional share.

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PLAN OF DISTRIBUTION

We are offering 2,740,722 shares of our Senior Common Stock at a price to the public of $15.00 per share and 499,263 shares of our Senior Common Stock to be issued pursuant to our distribution reinvestment plan at a price of $15.00 per share to those stockholders who elect to participate in such distribution reinvestment plan as described in this prospectus supplement. We reserve the right to reallocate shares between our primary offering and our offering pursuant to our distribution reinvestment plan in our sole and absolute discretion. The Dealer Manager is not required to sell any specific number or dollar amount of shares of Senior Common Stock but will use its “best efforts” to sell the shares offered by this prospectus supplement. The minimum permitted purchase of shares of Senior Common Stock is 200 shares having an aggregate minimum purchase price of $3,000. We reserve the right, however, to waive the minimum purchase requirement in our sole and absolute discretion.

The primary offering, will terminate on the earlier of (i) March 28, 2015, unless earlier terminated or extended by our Board, or (ii) the date on which 2,740,722 shares of Senior Common Stock are sold hereunder. If we extend the primary offering period beyond March 28, 2015, we will update this prospectus supplement accordingly. We may extend the offering period for the 499,263 shares of Senior Common Stock being offered hereby under our distribution reinvestment plan beyond the termination of the primary offering and until we have sold all of the shares allocated to the distribution reinvestment plan through the reinvestment of distributions. We may, however, terminate this offering at any time in our sole and absolute discretion.

The Dealer Manager is a securities broker-dealer registered with the SEC and a member firm of FINRA or SIPC. The Dealer Manager, which is owned by Mr. Gladstone, our chairman and chief executive officer, specializes in raising public and private equity funding for U.S. fund managers and performing various investment banking activities.

Compensation of Dealer Manager and Participating Broker-Dealers

We will pay the Dealer Manager selling commissions of 7% of the gross offering proceeds generated by the primary offering. We will pay the Dealer Manager 3% of the gross offering proceeds generated by the primary offering as compensation for acting as dealer manager and for expenses incurred in connection with the marketing for, and due diligence of, the primary offering. We will not pay selling commissions or any Dealer Manager fees with respect to shares purchased pursuant to our distribution reinvestment plan nor will we pay referral or similar fees to any accountants, attorneys or other persons in connection with the distribution of shares of Senior Common Stock.

We expect that the Dealer Manager will authorize other broker-dealers that are members of FINRA to sell shares of Senior Common Stock. The Dealer Manager will reallow all of its selling commissions attributable to a participating broker-dealer and may also reallow a portion of its Dealer Manager fee earned in respect of the proceeds generated by the participating broker-dealer to such participating broker-dealer as a non-accountable marketing allowance. The amount of the reallowance to any participating broker-dealer will be determined by the Dealer Manager in its sole and absolute discretion.

Any reduction in commissions in instances where lesser or no commissions or Dealer Manager fees are paid by us in connection with the sale of shares of Senior Common Stock will reduce the effective purchase price per share to the investor involved but will not materially alter the net proceeds payable to us as a result of such sale. Distributions will be the same with respect to all shares whether or not the purchaser received a discount. Investors for whom we pay reduced commissions or Dealer Manager fees will receive higher returns on their investments in shares of Senior Common Stock as compared to investors for whom we do not pay reduced commissions and Dealer Manager fees.

The table below sets forth the nature and estimated amount of all items that are viewed as “underwriting compensation” by FINRA, assuming that we sell all of the shares of Senior Common Stock offered pursuant to this prospectus supplement.

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Dealer Manager and Participating Broker-Dealer Compensation

We will also reimburse the Dealer Manager for reimbursements it may make to participating broker-dealers for bona fide accountable due diligence expenses presented on detailed and itemized invoices.

We or our affiliates also may provide permissible forms of non-cash compensation to registered representatives of our Dealer Manager and any participating broker-dealers, including gifts. In no event shall such gifts exceed an aggregate value of $100 per annum per participating salesperson or be pre-conditioned upon the achievement of a sales target. The value of any such items will be considered underwriting compensation in connection with this offering.

To the extent permitted by law and our charter, we will indemnify the Dealer Manager and any participating broker-dealers against certain civil liabilities, including certain liabilities arising under the Securities Act and liabilities arising from breaches of our representations and warranties contained in the Dealer Manager Agreement. However, the SEC takes the position that indemnification against liabilities arising under the Securities Act is against public policy and is not enforceable.

The total amount of underwriting compensation, including selling commissions and Dealer Manager fees paid or reimbursed by us, our Adviser or any other source in connection with this offering, will not exceed 10% of the gross proceeds of our primary offering. All organization and offering expenses, including selling commissions and Dealer Manager fees, will be capped at 15% of the gross proceeds of the offering.

Subscription Procedures

If you choose to purchase shares of Senior Common Stock in this offering, you must complete a Subscription Agreement, a form of which is appended to this prospectus supplement as Appendix A , specify the number of shares that you wish to purchase and pay for the shares at the time you subscribe. You should pay for your shares by check made payable to “BB&T, as escrow agent for Gladstone Commercial Corporation” or as otherwise instructed by the Dealer Manager or any participating broker-dealer. We will place your subscription payment in an account held by our escrow agent, BB&T Corporation, which funds will be held in trust for your benefit until the next closing date. We will hold two closings per month for our primary offering. The closing dates were randomly selected prior to the commencement of the primary offering, and will occur once between the 1st and 15th of each month and once between the 16th and last day of each month. On any such closing date, we will either accept or reject your subscription and (i) if accepted, we will transfer your funds to our general account, and you will receive a confirmation of your subscription, or (ii) if rejected, we will return your funds, without interest, within 10 business days thereafter. Subscriptions will be effective only upon our acceptance, and we reserve the right to reject any subscription either in whole or in part for whatever reason.

The Dealer Manager and any participating broker-dealer who sells shares of Senior Common Stock on our behalf has the responsibility to make every reasonable effort to determine that the purchase of shares is appropriate for the investor. In making this determination, the Dealer Manager and any participating broker-dealer will rely upon relevant information provided by the investor, including information as to the investor’s age, investment objectives, investment experience, income, net worth, financial situation, other investments and other pertinent information. Each investor should be aware that the Dealer Manager and any

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participating broker-dealer will be responsible for determining whether this investment is appropriate for your portfolio. However, you are required to represent and warrant in the Subscription Agreement that you have received a copy of this prospectus supplement and have had sufficient time to review this prospectus supplement.

The Dealer Manager and any participating broker-dealer shall maintain records of the information used to determine that an investment in shares of Senior Common Stock is suitable and that an investment in shares is suitable and appropriate for an investor. These records are required to be maintained for a period of at least six years.

Minimum Purchase Requirements

The minimum permitted purchase of shares of Senior Common Stock is 200 shares having an aggregate minimum purchase price of $3,000. We reserve the right, however, to waive the minimum purchase requirement in our sole and absolute discretion. In order to satisfy the minimum purchase requirement for retirement plans, unless otherwise prohibited by state law, a husband and wife may jointly contribute funds from their separate IRAs, provided that each such contribution is made in increments of $100. You should note that an investment in shares of Senior Common Stock will not, in itself, create a retirement plan and that, in order to create a retirement plan, you must comply with all applicable provisions of the Code.

Stockholders who desire to purchase additional shares of Senior Common Stock after their initial investment may do so by obtaining an Additional Investment Form from the Dealer Manager or any participating broker-dealer, and completing, executing and delivering the Additional Investment Form, along with a check for the subscription amount, payable to “BB&T, as escrow agent for Gladstone Commercial Corporation” to the Dealer Manager’s address set forth above. See “Questions and Answers about this Offering — Who can help answer my questions?” in this prospectus supplement. The terms, conditions, representations and warranties in the holder’s Subscription Agreement executed upon the holder’s initial investment in shares of Senior Common Stock shall be applicable to the additional investment. Any questions about subscriptions or additional contributions should be directed to the Dealer Manager at the contact information set forth above. See “Questions and Answers about this Offering — Who can help answer my questions?” in this prospectus supplement.

You may not transfer your shares of Senior Common Stock in a manner that causes you or your transferee to own fewer than the number of shares that are required for the minimum purchase described above, except in the following circumstances: transfers by gift; transfers by inheritance; intrafamily transfers; family dissolutions; transfers to affiliates; and transfers by operation of law.

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SUPPLEMENTAL SALES MATERIAL

In addition to this prospectus supplement, we may utilize additional sales materials in connection with the offering of shares of Senior Common Stock although we will do so only when accompanied by or preceded by the delivery of this prospectus supplement and the accompanying prospectus. These supplemental sales materials may include information relating to this offering, property brochures and articles and publications concerning real estate.

We are offering shares of Senior Common Stock only by means of this prospectus supplement and the accompanying prospectus. Although the information contained in our supplemental sales materials will not conflict with any of the information contained in this prospectus supplement and the accompanying prospectus, the supplemental materials do not purport to be complete and are not, and shall not be deemed to be, except as described below, a part of this prospectus supplement or the accompanying prospectus or incorporated into any other filings that we make with the SEC.

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ERISA CONSIDERATIONS

The following is a summary of material considerations associated with an investment in our shares by a qualified employee pension benefit plan or an IRA. This summary is based upon provisions of ERISA and the Code, as of the date of this prospectus supplement, and the relevant regulations, opinions and other authority issued by the Department of Labor and the IRS. We cannot assure you that there will not be adverse tax or labor decisions or legislative, regulatory or administrative changes that would significantly modify the statements expressed in this prospectus supplement. Any such changes may apply to transactions entered into prior to the date of their enactment. This discussion does not purport to deal with all aspects of ERISA or the Code that may be relevant to particular investors in light of their particular circumstances and a prospective investor is advised to consult its financial and legal advisers.

Any discussion of U.S. federal tax issues set forth in this prospectus supplement was written in connection with the promotion and marketing by the Company, the Adviser and the Dealer Manager of the shares of Senior Common Stock. Such discussion is not intended or written to be legal or tax advice to any person and is not intended or written to be used, and cannot be used, by any person for the purpose of avoiding any U.S. federal tax penalties that may be imposed on such person. You should seek advice based on your particular circumstances from an independent tax adviser.

Each fiduciary of an employee pension benefit plan subject to ERISA (such as a profit sharing, Section 401(k) or pension plan) or any other retirement plan or account subject to Section 4975 of the Code, such as an IRA, seeking to invest plan assets in shares of Senior Common Stock must, taking into account the facts and circumstances of each such plan or IRA, consider, among other matters:

Under ERISA, a plan fiduciary’s responsibilities include the following duties:

ERISA also requires that, with certain exceptions, the assets of an employee benefit plan be held in trust and that the trustee, or a duly authorized named fiduciary or investment manager, have exclusive authority and discretion to manage and control the assets of the benefit plan.

Prohibited Transactions

Generally, both ERISA and the Code prohibit benefit plans from engaging in certain transactions involving plan assets with specified parties, such as sales or exchanges or leasing of property, loans or other extensions of credit, furnishing goods or services, or transfers to, or use of, plan assets. The specified parties are referred to as

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“parties-in-interest” under ERISA and as “disqualified persons” under the Code. These definitions generally include both parties owning threshold percentage interests in an investment entity and “persons providing services” to the benefit plan, as well as employer sponsors of the benefit plan, fiduciaries and other individuals or entities affiliated with the foregoing. A person generally is a fiduciary with respect to a benefit plan if, among other things, the person has discretionary authority or control with respect to plan assets, has any discretionary responsibility in the benefit plan’s administration or provides investment advice for a fee with respect to plan assets. Under current Department of Labor, or DOL, regulations, a person shall be deemed to be providing investment advice if that person renders advice as to the advisability of investing in shares of Senior Common Stock, that person regularly provides investment advice to the benefit plan pursuant to a mutual agreement or understanding that such advice will serve as the primary basis for investment decisions, and that the advice will be individualized for the benefit plan based upon its particular needs.

If we are deemed to hold plan assets, our management could be characterized as fiduciaries with respect to such assets, and each would be deemed to be a party-in-interest under ERISA and a disqualified person under the Code with respect to investing benefit plans. Whether or not we are deemed to hold plan assets, if we or our affiliates are affiliated with a benefit plan investor, we might be a disqualified person or party-in-interest with respect to such benefit plan investor, resulting in a prohibited transaction merely upon investment by such benefit plan in shares of Senior Common Stock.

Plan Asset Considerations

In order to determine whether an investment in shares of Senior Common Stock by a benefit plan creates or gives rise to the potential for either prohibited transactions or a commingling of assets as referred to below, a fiduciary must consider whether an investment in our shares will cause our assets to be treated as assets of the investing benefit plan. ERISA Section 3(42) generally provides that “plan assets” means plan assets as defined in regulations issued by the DOL (the Plan Assets Regulation). Those regulations provide guidelines as to whether, and under what circumstances, the underlying assets of an entity will be deemed to constitute assets of a benefit plan when the plan invests in that entity. Under the Plan Assets Regulation, the assets of an entity in which a benefit plan makes an equity investment will generally be deemed to be “plan assets,” unless one of the exceptions to this general rule applies.

In the event that our underlying assets were treated as plan assets, our management would be treated as fiduciaries with respect to each benefit plan stockholder and an investment in shares of Senior Common Stock might constitute an ineffective delegation of fiduciary responsibility to our Adviser, and expose the fiduciary of the benefit plan to co-fiduciary liability under ERISA for any breach by our Adviser of the fiduciary duties mandated under ERISA. Further, if our assets are deemed to be “plan assets,” an investment by an IRA in shares of Senior Common Stock might be deemed to result in an impermissible commingling of IRA assets with other property.

If our Adviser or its affiliates were treated as fiduciaries with respect to benefit plan stockholders, the prohibited transaction restrictions of ERISA and the Code would apply to any transaction involving our assets. These restrictions could, for example, require that we avoid transactions with persons that are affiliated with or related to us or our affiliates or require that we restructure our activities in order to obtain an administrative exemption from the prohibited transaction restrictions. Alternatively, we might have to provide benefit plan stockholders with the opportunity to sell their shares to us or we might dissolve.

If a prohibited transaction were to occur, the Code imposes an excise tax equal to 15% of the amount involved and authorizes the IRS to impose an additional 100% excise tax if the prohibited transaction is not “corrected” in a timely manner. These taxes would be imposed on any disqualified person who participates in the prohibited transaction. In addition, our Adviser and possibly other fiduciaries of benefit plan stockholders subject to ERISA who permitted the prohibited transaction to occur or who otherwise breached their fiduciary responsibilities (or a non-fiduciary participating in a prohibited transaction) could be required to restore to the

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benefit plan any profits they realized as a result of the transaction or breach and repay any losses incurred by the benefit plan as a result of the transaction or breach. With respect to an IRA that invests in shares of Senior Common Stock, the occurrence of a prohibited transaction involving the individual who established the IRA, or his or her beneficiary, would cause the IRA to lose its tax-exempt status under Section 408(e)(2) of the Code.

The Plan Assets Regulation provides that the underlying assets of an entity such as a REIT will be treated as assets of a benefit plan investing therein unless the entity satisfies one of the exceptions to the general rule.

Exception for Insignificant Participation by Benefit Plan Investors. The Plan Assets Regulation provides that the assets of an entity will not be deemed to be plan assets if equity participation in the entity by employee benefit plans is not significant. The Plan Asset Regulation provides that equity participation in an entity by benefit plan investors is “significant” if at any time 25% or more of the value of any class of equity interest is held by benefit plan investors. The term “benefit plan investors” is defined for this purpose under ERISA Section 3(42) and includes any “employee benefit plan,” as defined, and subject to Part 4 of Title I of, ERISA, any “plan,” as defined in and subject to Section 4975 of the Code, and any entity whose underlying assets include plan assets by reason of an employee benefit plan’s or a plan’s investment in such entity. In calculating the value of a class of equity interests, the value of any equity interests held by us or any of our affiliates must be excluded as must any equity interests held by a person (other than a benefit plan) who has discretionary authority or control with respect to our assets or any person who provides investment advice for a fee (direct or indirect) with respect to our assets, or any affiliate of such persons.

In order to avoid causing our underlying assets to be plan assets, we intend to restrict the aggregate investment by benefit plan investors to under 25% of the total value of the shares of Senior Common Stock (not including the value of shares held by us, the Adviser, any person (other than a benefit plan) who has discretionary authority or control with respect to our assets or any person who provides investment advice for a fee (direct or indirect) with respect to our assets, or any affiliates thereof). Furthermore, because the 25% test is ongoing, it not only restricts additional investment by benefit plan investors, but can also cause us to require that existing benefit plan investors redeem their shares of Senior Common Stock in the event that other investors redeem or otherwise transfer their shares of Senior Common Stock. If rejection of subscriptions or such mandatory redemptions are necessary, as determined by the Company, to avoid causing our assets to be plan assets, the Company will effect such rejections or redemptions in such manner as the Company, in its sole discretion, determines.

Other Prohibited Transactions

Regardless of whether shares of Senior Common Stock qualify for the insignificant participation exception of the Plan Assets Regulation, a prohibited transaction could occur if we, our Adviser, the Dealer Manager, any participating broker-dealer, any of their affiliates or any other person listed in ERISA Section 3(14) or Section 4975(e)(2) of the Code is a party-in-interest or disqualified person (within the meaning of such sections) with respect to any benefit plan purchasing shares of Senior Common Stock. Accordingly, unless an administrative or statutory exemption applies, shares of Senior Common Stock should not be purchased by a benefit plan with respect to which any of the above persons is a party-in-interest or disqualified person.

Valuation

A fiduciary of an employee benefit plan subject to ERISA is required to determine annually the fair market value of each asset of the plan as of the end of the plan’s fiscal year and to file a report reflecting that value with the Department of Labor. When the fair market value of any particular asset is not available, the fiduciary is required to make a good faith determination of that asset’s fair market value assuming an orderly liquidation at the time the determination is made. In addition, a trustee or custodian of an IRA must provide an IRA participant with a statement of the value of the IRA each year. In discharging its obligation to value assets of a plan, a fiduciary subject to ERISA must act consistently with the relevant provisions of the plan and the general fiduciary standards of ERISA.

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To assist fiduciaries in fulfilling their valuation and annual reporting responsibilities with respect to ownership of shares of Senior Common Stock, beginning with the quarter ending September 30, 2014, we will determine the value per share of Senior Common Stock on a quarterly basis. This value will be determined as of the last day of each quarter and will be posted to our website at http://www.GladstoneCommercial.info.

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LEGAL MATTERS

Certain legal matters will be passed upon for us by Bass, Berry & Sims PLC, Memphis, Tennessee. Certain matters of Maryland law, including the validity of the shares of Senior Common Stock to be issued in connection with this offering, will be passed upon for us by Venable LLP, Baltimore, Maryland.

EXPERTS

The financial statements of Gladstone Commercial Corporation and management’s assessment of the effectiveness of internal control over financial reporting (which is included in Management’s Report on Internal Control over Financial Reporting) incorporated in this prospectus supplement by reference to the Annual Report on Form 10-K for the year ended December 31, 2012 and the Historical Summary of Revenue for the year ended December 31, 2012 of 717 East Parmer Lane, included on page 4 of Gladstone Commercial Corporation’s Current Report on Form 8-K, dated August 29, 2013, have been so incorporated in reliance on the reports of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

WHERE YOU CAN FIND MORE INFORMATION

The SEC allows us to “incorporate by reference” the information we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus supplement and the accompanying prospectus, and the information that we file subsequently with the SEC prior to the completion of this offering will automatically update and supersede this information.

We also incorporate by reference into this prospectus supplement additional documents that we may file with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, from the date of this prospectus supplement until all of the securities offered by this prospectus supplement have been sold or the offering of these securities is otherwise terminated, provided, however, that information “furnished” under Item 2.02 or Item 7.01 of Form 8-K or other information “furnished” to the SEC which is not deemed filed is not incorporated by reference in this prospectus supplement and in the accompanying prospectus. Information that we subsequently file with the SEC will automatically update and may supersede information in this prospectus supplement, the accompanying prospectus and information previously filed with the SEC.

You may request a copy of these filings (other than exhibits, unless the exhibits are specifically incorporated by reference into these documents) at no cost by sending us a written request at the following address: Gladstone Commercial Corporation, 1521 Westbranch Drive, Suite 200, McLean, Virginia 22102, Attention: Investor Relations or by calling us at (703) 287-5893.

We are a public company and file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy any document we file at the SEC’s public reference room at 100 F Street, NE, Washington, D.C. 20549. You may request copies of these documents by writing to the SEC and paying a fee for the copying cost. Please call the SEC at 1-800-SEC-0330 for more information about the operation of the public reference room. Our SEC filings are also available to the public at the SEC’s website at http://www.sec.gov. We also make available free of charge through our website our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act, as well as the definitive proxy statement and Section 16 reports on Forms 3, 4 and 5. Our website address is http://www.GladstoneCommercial.com. However, the information located on, or accessible from, our website is not, and shall not be deemed to be, a part of this prospectus supplement or the accompanying prospectus or incorporated into any other filings that we make with the SEC.

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PRIVACY NOTICE

We are committed to protecting your privacy. This privacy notice explains our privacy policies and supersedes any other privacy notice that you may have previously received from us.

We will safeguard, according to strict standards of security and confidentiality, all information that we receive about you. The only information that we collect from you is your name, address, ownership of our capital stock and social security number. This information is used only so that we can send you information about us voluntarily or as may be required by law.

We do not share this information with any non-affiliated third party except as described below.

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Appendix A

SUBSCRIPTION AGREEMENT

1. INVESTMENT

State of Sale:             Amount of Subscription: $                                                     

2. INVESTMENT TYPE (CHECK ONE BOX ONLY)

3. INVESTOR INFORMATION            (SSN REQUIRED)

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4. INVESTMENT TITLE            (SSN OR TIN REQUIRED)

Please print names in which shares of common stock are to be registered. Include trust name if applicable. If IRA or qualified plan, include both custodian and investor names and Tax ID Numbers. If same as above, write same.