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, 2011

OR

For the transition period from              to             

Commission File Number: 1-7183

TEJON RANCH CO.

(Exact name of Registrant as specified in its Charter)

P.O. Box 1000, Lebec, California 93243

(Address of principal executive office)

Registrant’s telephone number, including area code: (661) 248-3000

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

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 ((§232.405of this chapter) during the preceding 12 months (or for 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.  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 definition of “accelerated filer,” “large 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 Act).    Yes  ¨    No  x

The aggregate market value of registrant’s Common Stock, par value $.50 per share, held by persons other than those who may be deemed to be affiliates of registrant on June 30, 2011 was $676,984,299 based on the last reported sale price on the New York Stock Exchange as of the close of business on that date.

The number of the Company’s outstanding shares of Common Stock on February 25, 2012 was 19,987,559 shares.

DOCUMENTS INCORPORATED BY REFERENCE:

Portions of the Proxy Statement for the Annual Meeting of Stockholders to be held on May 8, 2012 relating to the directors and executive officers of the Company are incorporated by reference into Part III.

EXPLANATORY NOTE

This Form 10-K/A, Amendment No. 1 to our Annual Report on Form 10-K for the fiscal year ended December 31, 2011, as filed with the Securities and Exchange Commission on March 12, 2012 (the “Original Filing”) is being filed solely to furnish Exhibit 99.1 to the Original Filing. Exhibit 99.1 contains the financial statements of Petro Travel Plaza Holdings LLC.

Except for the item described above, no other information in the Original Filing is amended hereby, and this amendment does not reflect events occurring after the Original Filing or modify or update those disclosures affected by subsequent events. Accordingly, this Form 10-K/A should be read in conjunction with the Original Filing and our other filings with the Securities and Exchange Commission.

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PART IV

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Signatures

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

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