UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

AMENDMENT NO. 1

For the Fiscal Year Ended December 31, 2010

OR

For the transition period from              to

Commission File Number: 001-34403

Territorial Bancorp Inc.

(Name of Registrant as Specified in its Charter)

(808) 946-1400

(Registrant’s Telephone Number including area code)

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

Common Stock, par value $0.01 per share

(Title of Class)

The NASDAQ Stock Market LLC

(Name of exchange on which registered)

Securities Registered Under Section 12(g) of the Exchange 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 of 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 reports), and (2) has been subject to such requirements for the past 90 days.

(1)    YES  x    NO  ¨

(2)    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 during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  ¨    No  ¨

Indicate by a 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 this Form 10-K or any amendments to this Form 10-K.  x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or 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    x  NO

The aggregate value of the voting common equity held by non-affiliates of the Registrant, computed by reference to the closing price of the Registrant’s shares of common stock as of June 30, 2010 ($18.95) was $226.1 million.

As of February 28, 2011, there were 12,127,068 shares outstanding of the Registrant’s common stock.

DOCUMENTS INCORPORATED BY REFERENCE

None.

TERRITORIAL BANCORP, INC.

FORM 10-K/A

Explanatory Note

This amendment to FORM 10-K/A is being filed to include exhibits that were inadvertently omitted from the initial filing.

PART IV

(a)    Financial Statements

The following documents are filed as part of this annual report:

Not applicable.

SIGNATURES

In accordance with Section 13 of the Exchange Act, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.