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, 2015

or

For the transition period from                      to                     

Commission file number: 333-136110

GTJ REIT, INC.

(Exact name of registrant as specified in its charter)

(516) 693-5500

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(g) of the Act: NONE

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 (§229.405 of this chapter) 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 this Form 10-K or any amendment to this Form 10-K.    Yes  ¨    No  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 the definitions of “large accelerated filer,” “accelerated filer,” and “small 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

State the aggregate market value of the voting and non-voting common equity held by non-affiliates computed by reference to the price at which the common equity was last sold, or the average bid and asked priced of such common equity, as of the last business day of the registrant’s most recently completed second fiscal quarter: N/A

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the last practicable date: As of March 24, 2016, there were 13,820,434 shares of common stock issued and outstanding.

EXPLANATORY NOTE

GTJ REIT, Inc., (the “Company”) is filing this Amendment No. 1 on Form 10-K/A (the “Amendment No. 1”) to its Annual Report on Form 10-K for the year ended December 31, 2015 which was originally filed with the Securities and Exchange Commission on March 29, 2016 (the “Original Filing”), for the sole purpose of including a copy of the signed consent by of the Company’s independent accounting firm of BDO USA, LLP as Exhibit 23.1 which was inadvertently omitted in the Original Filing. Accordingly, this Amendment No. 1 consists only of the facing page, this Explanatory Note, Part IV (Item 15), and the exhibits identified below as being filed herewith.

This Amendment No. 1 continues to speak as of the date of the Original Filing, and we have not updated the disclosures contained in this Amendment No. 1 to reflect any events that occurred at a date subsequent to the filing of the Original Filing. The filing of this Amendment No. 1 is not a representation that any statements contained in items of the Original Filing (other than that information being amended) are true or complete as of any date subsequent to the date of the Original Filing. Accordingly, this Amendment No. 1 should be read in conjunction with the Original Filing and with our public filings made with the Securities and Exchange Commission subsequent to the Original Filing.

Pursuant to Rule 12b-15 under the Securities Exchange Act of 1934, as amended, the certifications pursuant to Section 302 and Section 906 of the Sarbanes-Oxley Act of 2002, filed and furnished, respectively, as exhibits to the Original Filing have been re-executed and re-filed as of the date of this Amendment No. 1 and are included as exhibits hereto.

Part IV

Item 15.Exhibits

23.1Consent of Independent Registered Public Accounting Firm BDO USA, LLP.

31.1Certification of CEO of GTJ REIT, Inc. pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

31.2 Certification of CFO of GTJ REIT, Inc. pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

32.1 Certification of CEO of GTJ REIT, Inc. pursuant to 18 U.S.C. ss.1350.

32.2 Certification of CFO of GTJ REIT, Inc. pursuant to 18 U.S.C. ss.1350.

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.