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

February 27, 2013

Date of Report (Date of earliest event reported)

WESTERN GAS EQUITY PARTNERS, LP

(Exact name of Registrant as specified in its charter)

1201 Lake Robbins Drive

The Woodlands, Texas 77380-1046

(Address of principal executive offices)

(832) 636-6000

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing 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.

The information set forth below in Item 2.01 is incorporated herein by reference.

Item 2.01 Completion of Acquisition or Disposition of Assets.

On March 1, 2013, our consolidated subsidiary, Western Gas Partners, LP (“WES”) completed its previously announced acquisition (the “Acquisition”) of a 33.75% interest in two gathering systems that serve production from the Marcellus shale in north-central Pennsylvania, pursuant to the terms and conditions of a Contribution Agreement (the “Contribution Agreement”) dated February 27, 2013, among Anadarko Marcellus Midstream, L.L.C. (the “Contributing Party”), and WES, Western Gas Operating, LLC (“Western Gas Operating”) and WGR Operating, LP (the “Operating Partnership” and together with Western Gas Operating and WES, the “Recipient Parties”), and for certain limited purposes, Anadarko Petroleum Corporation (“Anadarko”) and Anadarko E&P Onshore LLC (“Anadarko E&P”). All of the parties are subsidiaries or affiliates of Anadarko. The consideration paid by WES for the Acquisition consisted of $465.5 million in cash and 449,129 common units of WES (the “Common Units”). WES funded the cash consideration through approximately (i) $250 million in borrowings under its revolving credit facility (including refinancings thereof, the “Revolving Loans”) and (ii) $215.5 million of cash on hand. The above summary is qualified in its entirety by reference to the Contribution Agreement, a copy of which is filed as an exhibit hereto as Exhibit 2.1.

In connection with the Acquisition, Western Gas Holdings, LLC, our wholly owned subsidiary and the general partner of WES (the “General Partner”), and Anadarko E&P entered into an indemnification agreement (the “AEP Indemnification”) whereby Anadarko E&P will indemnify the General Partner for any recourse liability it may have for the Revolving Loans. The General Partner and Western Gas Resources, Inc. (“WGRI”) also amended and restated the indemnity agreement between them (the “WGRI Indemnification”) to reduce the amount for which WGRI would indemnify the General Partner by an amount equal to any amounts payable to the General Partner under the AEP Indemnification. The above summaries of the AEP Indemnification and the WGRI Indemnification are qualified in their entirety by reference to the AEP Indemnification and WGRI Indemnification, copies of which are filed as exhibits hereto as Exhibits 10.1 and 10.2, respectively.

Relationships

The terms of the Acquisition were unanimously approved by the Board of Directors of WES’s General Partner and by the WES Board’s special committee. The WES special committee, a committee comprised of three independent members of the General Partner’s Board of Directors, retained independent legal and financial advisors to assist it in evaluating and negotiating the Acquisition. In approving the Acquisition, the WES special committee based its decision in part on an opinion from the independent financial advisor that the consideration to be paid by WES was fair, from a financial point of view, to WES.

After giving effect to the issuance of the Common Units to the Contributing Party in connection with the Acquisition, Anadarko indirectly owns, through the Contributing Party and Western Gas Equity Partners, LP: (i) the General Partner, which holds (x) all of the outstanding general partner units of WES, representing a 2.0% general partner interest in WES, and (y) all of the incentive distribution rights in WES, which entitle the General Partner to specified increasing percentages of cash distributions as WES’s per-unit cash distributions increase, and (ii) 49,745,334 common units, representing an aggregate 46.6% limited partner interest in WES, based on the number of common units outstanding as of March 1, 2013.

Item 2.03 Creation of a Direct Financial Obligation.

The information set forth under Item 2.01 above with respect to the borrowings under the revolving credit facility is incorporated herein by reference.

Item 7.01 Regulation FD Disclosure.

On February 27, 2013, WES made an announcement regarding the Acquisition. A copy of the press release announcing the transaction is attached hereto as Exhibit 99.1.

Item 8.01 Other Events.

On March 1, 2013 and in connection with the consummation of the transactions contemplated by the Contribution Agreement, WES entered into Amendment No. 10 to the First Amended and Restated Agreement of Limited Partnership of WES (the “Amendment”), to be effective March 1, 2013. The Amendment permitted WES to make a special, one-time cash distribution to the Contributing Party (without a corresponding distribution to the General Partner or the limited partners of WES) in an amount equal to the cash consideration.

The foregoing description is qualified in its entirety by reference to the full text of the Amendment, a copy of which is attached to this Current Report on Form 8-K as Exhibit 3.1 and is incorporated into this Item 8.01 by reference.

Item 9.01 Financial Statements and Exhibits.

(a) Financial Statements of Business Acquired.

The registrant will file the financial statements required by this Item not later than 71 days after the date on which this Form 8-K is required to be filed.

(b) Pro Forma Financial Information.

The registrant will file the financial statements required by this Item not later than 71 days after the date on which this Form 8-K is required to be filed.

(d) Exhibits

SIGNATURES

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 hereunto duly authorized.

EXHIBIT INDEX