UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K/A

(Amendment No. 1)

(Mark One)

For the fiscal year ended December 31, 2012

OR

For the transition period from                      to                     

Commission File Number: 000-53644

Strategic Storage Trust, Inc.

(Exact name of Registrant as specified in its charter)

111 Corporate Drive, Suite 120, Ladera Ranch,

California 92694

(Address of principal executive offices)

(877) 327-3485

(Registrant’s telephone number)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

Common Stock, $0.001 par value per share

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ¨    No  x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.    Yes  ¨    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of the Form 10-K or any amendment of this Form 10-K.  x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See definitions of “large accelerated filer”, “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ¨    No  x

The aggregate market value of voting common stock held by non-affiliates was approximately $467,000,000 assuming a market value of $10.79 per share, as of June 30, 2012.

As of March 21, 2013, there were 47,235,295 outstanding shares of common stock of the registrant.

Documents Incorporated by Reference:

Registrant incorporates by reference in Part III (Items 10, 11, 12, 13 and 14) of this Form 10-K portions of its Definitive Proxy Statement for the 2013 Annual Meeting of Stockholders.

EXPLANATORY NOTE

The purpose of this Amendment No. 1 to the Registrant’s Annual Report on Form 10-K for the year ended December 31, 2012, filed with the Securities and Exchange Commission on March 29, 2013 (the “Form 10-K”), is solely to correct a typographical error contained in the Report of Independent Registered Public Accounting Firm, signed by Reznick Group, P.C., included in the financial statements contained within the Form 10-K. The report was inadvertently dated March 29, 2013 and should be dated March 29, 2012, as shown herein.

No other changes have been made to the Form 10-K. This Amendment No. 1 to the Form 10-K speaks as of the original filing date of the Form 10-K, does not reflect events that may have occurred subsequent to the original filing date, and does not modify or update in any way disclosures made in the Form 10-K.

The Report of Independent Registered Public Accounting Firm should be as follows:

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and

Stockholders of Strategic Storage Trust, Inc.

We have audited the accompanying consolidated balance sheet of Strategic Storage Trust, Inc. and Subsidiaries as of December 31, 2011 and the related consolidated statements of operations, comprehensive loss, stockholders’ equity, and cash flows for each of the years in the two-year period ended December 31, 2011. Strategic Storage Trust, Inc.’s management is responsible for these consolidated financial statements. Our responsibility is to express an opinion on these consolidated financial statements based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. The company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. Our audit included consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the company’s internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the consolidated financial position of Strategic Storage Trust, Inc. and Subsidiaries as of December 31, 2011 and the consolidated results of its operations and its cash flows for each of the years in the two-year period ended December 31, 2011, in conformity with accounting principles generally accepted in the United States of America.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Ladera Ranch, State of California, on April 5, 2013.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated: