UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported): January 28, 2013

DIAMONDBACK ENERGY, INC.

(Exact Name of Registrant as Specified in Charter)

(432) 221-7400

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K is intended to simultaneously satisfy the filing obligation of the Registrant under any of the following provisions:

Item 1.01. Entry into a Material Definitive Agreement.

On January 28, 2013, Diamondback E&P LLC (“Diamondback E&P”), a wholly-owned subsidiary of Diamondback Energy, Inc. (“Diamondback Energy”), entered into a Master Drilling Agreement (the “Drilling Agreement”) and a Master Field Services Agreement (the “Field Services Agreement” and, together with the Drilling Agreement, the “Services Agreements”), each effective as of January 1, 2013, with Bison Drilling and Field Services LLC (“Bison”). Under the Drilling Agreement, Bison committed to accept orders from Diamondback E&P for the use of two rigs for vertical wells owned by Bison and located in the Permian Basin of West Texas; provided, however, that Diamondback E&P may require from time-to-time, in its sole discretion, that one of the rigs be for horizontal wells. Under the Field Services Agreement, Diamondback E&P may order certain field services and/or purchase or lease goods, equipment or facilities from Bison, in each case to be defined in a separate order, in connection with the exploration for oil and natural gas, provided, however, that Diamondback E&P is not obligated to place, and Bison is not obligated to accept, orders for such services or goods. Each Services Agreement is terminable by either party on 30 days’ prior written notice, although neither party will be relieved of its respective obligations arising from a drilling contract or an accepted order, as the case may be, being performed prior to the termination of such Services Agreement. Bison had been performing drilling and field services for Diamondback Energy under prior master drilling and field services agreements, which have been replaced by the Services Agreements. Bison is owned by Gulfport Energy Corporation (“Gulfport”) and various entities controlled by Wexford Capital LP (“Wexford”). As of December 11, 2012, Gulfport and affiliates of Wexford beneficially owned approximately 21.4% and 44.4%, respectively, of Diamondback Energy’s outstanding common stock.

Further, on January 28, 2013, Diamondback E&P entered into an amendment to an existing employment agreement with each of Travis D. Stice, Diamondback Energy’s Chief Executive Officer, Teresa L. Dick, Diamondback Energy’s Senior Vice President and Chief Financial Officer, and Jeff White, Diamondback Energy’s Vice President—Operations. Each amendment provides that the annual base salary of such executive officer (which was a fixed amount in each existing employment agreement) can now be increased or decreased from time to time, but not decreased below the original base salary for such executive officer, by the compensation committee (the “Compensation Committee”) of Diamondback Energy’s Board of Directors. In addition, Mr. Stice’s employment agreement was amended to provide that he is eligible to receive a target annual bonus of 100% of his base salary upon achievement of his performance goals, that he will receive a minimum annual bonus of 66% of his base salary and that he will be eligible to receive an annual bonus of up to 133% of his base salary upon achievement of his performance goals. For 2013, the Compensation Committee set Mr. Stice’s base salary at $400,000. Each amendment was recommended and approved by the Compensation Committee.

The preceding summaries of the above-referenced agreements are qualified in their entirety by reference to the full text of such agreements, copies of which are attached as Exhibits 10.1, 10.2, 10.3, 10.4 and 10.5, respectively, to this Current Report on Form 8-K and the contents thereof are incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits

(d) Exhibits.

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SIGNATURE

Pursuant to the requirements 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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Exhibit Index

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