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, 2012

or

For the transition period from                      to                     

Commission file number: 001-16179

EPL Oil & Gas, Inc.

(Exact name of registrant as specified in its charter)

(713) 228 - 0711

Registrant’s telephone number, including area code:

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  x    No  ¨

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 (§ 229.405 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 is not contained herein, and will not be contained, to the best of the 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 the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

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

Indicate by check mark whether the registrant has filed all documents and reports required to be filed by Sections 12, 13 or 15(d) of the Securities Exchange Act of 1934 subsequent to the distribution of securities under a plan confirmed by a court.    Yes  x    No  ¨

The aggregate market value of the common stock held by non-affiliates of the registrant at June 30, 2012 based on the closing stock price as quoted on the New York Stock Exchange on that date was $484,063,819. As of February 28, 2013, there were 39,218,719 shares of the registrant’s common stock, par value $0.001 per share, outstanding.

DOCUMENTS INCORPORATED BY REFERENCE:

Portions of the Proxy Statement for the 2013 Annual Meeting of Stockholders of EPL Oil & Gas, Inc. have been incorporated by reference into Part III of this Annual Report on Form 10-K.

EXPLANATORY NOTE

EPL Oil & Gas, Inc. (the “Company”) is filing this Amendment No. 1 (“Form 10-K/A”) to its Annual Report on Form 10-K (“Form 10-K”) for the fiscal year ended December 31, 2012 filed with the Securities and Exchange Commission on March 7, 2013, solely to amend the consents filed as Exhibits 23.1, 23.2 and 23.3 to incorporate by reference all of the Company’s previously filed registration statements. The consents filed with the Form 10-K on March 7, 2013 inadvertently omitted certain previously filed registration statements. There are no other changes to the Form 10-K.

This Form 10-K/A speaks as of the original filing date of the Form 10-K, does not reflect events that may have occurred subsequent to the original filing date, and does not modify or update in any way disclosures made in the original Form 10-K.

PART IV

(a)(3) The following documents are filed as part of this report:

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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.

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