Westaff (WSTF)

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 10-K/A
(Amendment No.1)

ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
EXCHANGE ACT OF 1934
FOR THE FISCAL YEAR ENDED NOVEMBER 3, 2007

WESTAFF, INC.
(Exact name of registrant as specified in its charter)

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 405 of the Securities Act.    Yes o No ý

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

        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 ý No o

        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 this Form 10-K or any amendment to this Form 10-K.    ý

        Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer. See definition of "accelerated filer and large accelerated filer" in Rule 12b-2 of the Exchange.

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

        As of April 14, 2007, the aggregate market value of the registrant's common stock held by non-affiliates of the registrant was $46,172,221 based on the closing sale price as reported on the Nasdaq National Market.

        As of January 26, 2008, the Registrant had outstanding 16,697,010 shares of Common Stock.

DOCUMENTS INCORPORATED BY REFERENCE

        The following documents (or portions thereof) are incorporated herein by reference:

        Portions of the Registrant's Proxy Statement for the 2008 Annual Meeting of Stockholders are incorporated herein by reference into Part III of this Form 10-K Report.

EXPLANATORY NOTE:

        This Amendment No. 1 to the Annual Report on Form 10-K of Westaff, Inc. (the "Registrant") amends the Registrant's Annual Report on Form 10-K for the fiscal year ended November 3, 2007 that was originally filed with the Securities and Exchange Commission on February 1, 2008 (the "Original Filing"). This Amendment No. 1 is being filed solely to amend the cover page of the Original Filing to correct the aggregate market value of the Registrant's common stock held by non-affiliates of the Registrant as of April 14, 2007. No other changes have been made to the Original Filing. This Amendment No. 1 does not amend or update any other information set forth in the Original Filing, and the Registrant has not updated disclosures contained therein to reflect any events subsequent to the filing of the Original Filing. This Amendment No. 1 consists solely of the amended cover page, this explanatory note, the signature page and the certifications required to be filed as exhibits hereto.

ITEM 15.    EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.

(a)

The following exhibits are filed as a part of this Amendment No. 1.

2

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.

3

QuickLinks

ITEM 15. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.