UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10–K/A

(Amendment No. 1)

For the fiscal year ended December 31, 2012

OR

Commission File Number 001-35010

QR ENERGY, LP

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (713) 452-2200

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 (§ 232.405 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 registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III or any amendment to the 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 “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  ¨    NO  x

As of June 29, 2012, the last business day of the registrant’s most recently completed second fiscal quarter; the aggregate market value of the Common Units held by non-affiliates was approximately $618,965,686, based on the closing price of $16.54 per unit on that date.

As of March 5, 2013, the registrant had 6,133,158 Class B Units, 16,666,667 Class C Convertible Preferred Units, 58,443,978 Common Units and 51,036 General Partner Units outstanding.

EXPLANATORY NOTE

The purpose of this Amendment No. 1 (this “Amendment”) to the Annual Report on Form 10-K of QR Energy, LP (the “Partnership”) for the year ended December 31, 2012, as originally filed with the Securities and Exchange Commission (the “SEC”) on March 6, 2013 (the “Original 10-K Filing”), is to amend certain information in the Exhibit Index included in Part IV, Item 15(a)(3) of the Original 10-K Filing (the “Original Exhibit Index”). The information in the Exhibit Index below marked as previously filed or as incorporated by reference is not amended by this Amendment.

The Partnership’s reserves report of Miller and Lents, Ltd. as of December 31, 2012, which was filed as Exhibit 99.1 to the Original 10-K Filing (the “Original Reserves Report”), did not state that the report was prepared for the purpose of inclusion as an exhibit to the Original 10-K Filing. The Original Reserves Report also refers to additional supplemental information such as Appendix 1 and Exhibits 1 through 23 which were not included in the Original Reserves Report.

Exhibit 99.1 filed with this Amendment contains the revised reserves report of Miller and Lents, Ltd. (the “Revised Reserves Report”), which states that the report was prepared for the purpose of inclusion as an exhibit to the Partnership’s Annual Report on Form 10-K. The Revised Reserves Report also provides the additional supplemental information referenced in the report as Appendix 1 and removes references to Exhibits 1 through 23, as we did not intend to include this supplemental information. Additionally, Exhibit 23.2, which contains the consent of Miller and Lents, Ltd. to the use of the reserves report by the Partnership in this Form 10-K/A, is being filed herewith.

As required by Rule 12b-15 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), new certifications of our principal executive officer and principal financial officer are being filed or furnished, as indicated, as exhibits to this Amendment. Other than to file Exhibits 99.1, 23.2 and the new certifications included as Exhibits 31.1, 31.2, 32.1 and 32.2, there are no changes from the Original Exhibit Index reflected in Item 15 of this Amendment. There were no changes to reserve information provided by the Original Reserves Report.

Except as described above, this Amendment does not modify or update the disclosures presented in the Original 10-K Filing in any way. Those sections of the Original 10-K Filing that are unaffected by this Amendment are not included herein. This Amendment continues to speak only as of the date of the Original 10-K Filing and it has no impact on the Partnership’s previously reported audited financial statements and notes thereto as of December 31, 2012. Furthermore, except to the extent stated herein, we have not updated the information in the Original 10-K Filing, and this Amendment does not reflect events occurring after the filing of the Original 10-K Filing. Accordingly, this Amendment should be read in conjunction with the Original 10-K Filing as well as the Partnership’s other filings made with the SEC pursuant to Section 13(a) or 15(d) of the Exchange Act subsequent to the filing of the Original 10-K Filing as information in such filings may update or supersede certain information contained in the Original 10-K Filing, as amended hereby.

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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.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities indicated on November 14, 2013.

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