UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of The

Securities Exchange Act of 1934

Date of Report (Date of Earliest Event Reported):

January 12, 2011

American Assets Trust, Inc.

(Exact name of registrant as specified in its charter)

(858) 350-2600

Registrant’s telephone number, including area code:

Not Applicable

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On January 12, 2011, American Assets Trust, Inc. (the “Registrant”) in connection with its initial public offering of 31,625,000 shares of its common stock, which included, 4,125,000 shares from the exercise in full of the underwriters’ overallotment option (the “Initial Public Offering”), entered into the Underwriting Agreement by and among the Registrant, the Operating Partnership, Merrill Lynch, Pierce, Fenner & Smith Incorporated, Wells Fargo Securities, LLC and Morgan Stanley & Co. Incorporated, acting as the representatives of the several underwriters named in Schedule A thereto.

On January 19, 2011, the Registrant closed its Initial Public Offering. In connection with the initial public offering and certain formation transactions, the Registrant entered into the following agreements, each dated as of January 19, 2011:

Amended and Restated Agreement of Limited Partnership of American Assets Trust, L.P.;

Registration Rights Agreement among American Assets Trust, Inc. and the persons named therein;

Tax Protection Agreement by and among American Assets Trust, Inc., American Assets Trust, L.P., and each partner set forth in Schedule I, Schedule II and Schedule III thereto;

Transition Services Agreement between American Assets, Inc. and American Assets Trust, L.P.;

Employment Agreement among American Assets Trust, Inc., American Assets Trust, L.P. and Ernest S. Rady;

Franchise License Agreement—Embassy Suites—Waikiki Beach Walk—Honolulu, Hawaii between Embassy Suites Franchise LLC and WBW Hotel Lessee, LLC; and

Copies of the agreements are filed as exhibits to this report and are incorporated herein by reference.

On January 19, 2011, the Registrant issued a press release announcing the closing of the Initial Public Offering and exercise in full of the underwriters’ overallotment option to purchase 4,125,000 shares of the Company’s common stock. A copy of the press release is attached as Exhibit 99.1.

(d) Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

January 19, 2011

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