Table of Contents

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 2)*

RESOLUTE ENERGY CORPORATION

(Name of Issuer)

COMMON STOCK, PAR VALUE $0.0001 PER SHARE

(Title of Class of Securities)

76116A108

(CUSIP Number)

Richard L. Covington

5221 N. O’Connor Blvd., Suite 1100

Irving, Texas 75039

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

May 14, 2013

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box  ¨.

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Table of Contents

2

Table of Contents

Natural Gas Partners VII, L.P. directly owns 1,078,595 shares of Common Stock of the Issuer and is deemed to indirectly beneficially own (i) 49,790 shares of Common Stock of the Issuer that are directly owned by NGP-VII Income Co-Investment Opportunities, L.P. by virtue of Natural Gas Partners VII, L.P.’s ownership of 100% of NGP Income Management, L.L.C., which is the sole general partner of NGP-VII Income Co-Investment Opportunities, L.P., and (ii) 8,333,472 shares of Common Stock of the Issuer deemed to be beneficially owned by Resolute Holdings, LLC by virtue of it and NGP-VII Income Co-Investment Opportunities, L.P.’s approximate 66% membership interest in Resolute Holdings, LLC, subject to certain adjustments in the future that could decrease such interest.

The Reporting Person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest therein, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of the reported securities for purposes of Section 16 or for any other purpose.

3

Table of Contents

4

Table of Contents

Resolute Holdings, LLC, is deemed to directly beneficially own 8,333,472 shares of Common Stock of the Issuer for purposes of this Schedule 13D even though certain of the shares of Common Stock directly owned by Resolute Holdings, LLC are subject to the limitations set forth in this Schedule 13D. The Reporting Person and NGP-VII Income Co-Investment Opportunities, L.P. have an approximately 66% membership interest in Resolute Holdings, LLC, subject to certain adjustments in the future that could decrease such interest. Thus, the Reporting Person may be deemed to be the indirect beneficial owner of the Common Stock of the Issuer deemed beneficially owned by Resolute Holdings, LLC.

The Reporting Person disclaims beneficial ownership of the reported securities except to the extent of its pecuniary interest therein, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of the reported securities for purposes of Section 16 or for any other purpose.

5

Table of Contents

6

Table of Contents

Resolute Holdings, LLC also directly owns 2,333,333 warrants (the “Sponsor Warrants”) acquired in connection with the Acquisition. Each Sponsor Warrant entitles the holder to purchase one share of Common Stock at a price of $13.00 per share commencing on the date of the closing of the Acquisition and ending five years from the Acquisition Closing Date.

Resolute Holdings, LLC also directly owns 4,600,000 warrants (the “Founders’ Warrants”) issued in the Acquisition. Each Founders’ Warrant entitles the holder to purchase one share of Common Stock at a price of $13.00 per share. The warrant exercise period of the Founders’ Warrants commenced on January 7, 2011 and ends on September 25, 2014.

Thus, for purposes of this Schedule 13D, Resolute Holdings, LLC is deemed to directly beneficially own 8,333,472 shares of Common Stock.

7

Table of Contents

TABLE OF CONTENTS

8

Table of Contents

This Amendment No. 2 to Schedule 13D (this “Amendment”) amends the joint Schedule 13D filed on February 17, 2010 by Kenneth A. Hersh, Natural Gas Partners VII, L.P. and Resolute Holdings, LLC, as amended by that certain Amendment No. 1 to Schedule 13D filed on February 23, 2011 (the “Original Schedule 13D”). This Amendment is being filed in order to reflect a decrease in the Reporting Persons’ beneficial ownership resulting from the sale by Natural Gas Partners VII, L.P. (“NGP VII”) and NGP-VII Income Co-Investment Opportunities, L.P. (“NGP VII Co-Invest”) of an aggregate of 5,437,500 shares of common stock of Resolute Energy Corporation (the “Issuer”) in a secondary offering that closed on May 14, 2013 (the “Offering”). As a result of the Offering, this Amendment amends the information disclosed in the Original Schedule 13D as set forth herein. Except as provided herein, this Amendment does not modify any of the information previously reported in the Original Schedule 13D. Capitalized terms used herein but not defined have the meanings ascribed to them in the Original Schedule 13D.

Item 1. Security and Issuer.

No modification is made to Item 1 of the Original Schedule 13D.

Item 2. Identity and Background.

No modification is made to Item 2 of the Original Schedule 13D.

Item 3. Source and Amount of Funds or Other Consideration.

No modification is made to Item 3 of the Original Schedule 13D.

Item 4. Purpose of Transaction.

Item 4 of the Original Schedule 13D is hereby supplemented as follows:

The Reporting Persons, in the normal course of their business, intend to evaluate the optimal management of their holdings, which could include from time to time disposal of shares of Common Stock, in the open market, in privately negotiated transactions, or otherwise, including based on perceived economic and stock market conditions.

Item 5. Interest in Securities of the Issuer.

The information in Item 5 of the Original Schedule 13D is hereby amended in its entirety to read as follows:

The percent of class provided for each Reporting Person is based on the Issuer having 63,631,145 total outstanding shares of Common Stock as of May 8, 2013, as reported on the Prospectus Supplement plus each of the following (i) 13,250,000 shares of Common Stock issued to the Underwriters by the Issuer as described in the Prospectus Supplement and (ii) 6,933,333 shares of Common Stock as the result of the conversion of 2,333,333 Sponsor Warrants and 4,600,000 Founders’ Warrants convertible into Common Stock.

NGP VII owns 100% of NGP Income Management, L.L.C. which serves as the general partner of NGP-VII Income Co-Investment. NGP VII may thus be deemed to possess shared voting and dispositive powers with respect to all of the shares of Common Stock owned directly by NGP-VII Co-Invest (49,790 shares (0.06%)).

NGP VII and NGP-VII Co-Invest have an approximately 66% membership interest in Resolute Holdings subject to certain adjustments in the future that could decrease such interest. Thus, NGP VII may be deemed to possess shared voting and dispositive powers with respect to all of the shares of Common Stock deemed beneficially owned by Resolute Holdings (8,333,472 shares (9.9%)).

9

Table of Contents

Therefore, NGP VII may be deemed to possess sole and shared voting and dispositive powers with respect to 9,461,857 shares (11.3%) of Common Stock.

Resolute Holdings also directly owns 2,333,333 warrants (the “Sponsor Warrants”) acquired in connection with the Acquisition. Each Sponsor Warrant entitles the holder to purchase one share of Common Stock at a price of $13.00 per share commencing on the date of the closing of the Acquisition and ending five years from the Acquisition Closing Date.

Resolute Holdings also directly owns 4,600,000 warrants (the “Founders’ Warrants”) issued in the Acquisition. Each Founders’ Warrant entitles the holder to purchase one share of Common Stock at a price of $13.00 per share. The warrant exercise period of the Founders’ Warrants commenced on January 7, 2011 and ends on September 25, 2014.

Thus, for purposes of this Schedule 13D, Resolute Holdings is deemed to directly beneficially own 8,333,472 shares (9.9%) of Common Stock.

The above Reporting Persons disclaim beneficial ownership of the reported securities except to the extent of their pecuniary interests therein, and this report shall not be deemed an admission that the Reporting Persons are the beneficial owners of the reported securities for purposes of Section 16 or for any other purpose.

Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.

No modification is made to Item 6 of the Original Schedule 13D.

Item 7. Material to be Filed as Exhibits.

10

Table of Contents

SIGNATURES

After reasonable inquiry and to the best of each of the undersigned’s knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: May 16, 2013

11

Table of Contents

Exhibit Index

12