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): June 19, 2013

HARVEST NATURAL RESOURCES, INC.

(Exact name of registrant as specified in its charter)

1177 Enclave Parkway, Suite 300

Houston, Texas 77077

(Address of principal executive offices) (Zip Code)

(281) 899-5700

(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 filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Item 4.01 Change in Registrant’s Certifying Accountant

On June 19, 2013, Harvest Natural Resources, Inc. (“we”, “us”, “our” or the “Company”), at the direction and with the unanimous approval of the Audit Committee (the “Audit Committee”) of the Company’s Board of Directors (the “Board”), dismissed PricewaterhouseCoopers LLP (“PwC”) as its independent registered public accounting firm and engaged UHY LLP (“UHY”) to become its new independent registered public accounting firm.

PwC’s reports on the Company’s consolidated financial statements for the fiscal years ended December 31, 2012 and 2011 did not contain any adverse opinion or a disclaimer of opinion, nor were those reports qualified or modified as to uncertainty, audit scope or accounting principles, except that PwC’s audit opinion on the Company’s financial statements as of and for the year ended December 31, 2012 (a) includes an explanatory paragraph expressing substantial doubt regarding the Company’s ability to continue as a going concern and (b) expresses an opinion that the Company did not maintain, in all material respects, effective internal control over financial reporting as of December 31, 2012, because of material weaknesses in internal control over financial reporting as described below.

During the Company’s two most recent fiscal years ended December 31, 2011 and 2012, and the subsequent interim period through June 19, 2013, there were no disagreements with PwC on any matters of accounting principles and practices, financial statement disclosure, or auditing scope or procedure that, if not resolved to the satisfaction of PwC, would have caused it to make reference to the disagreement in connection with its reports on the Company’s financial statements.

Except for the six material weaknesses in the Company’s internal control over financial reporting as described by the Company in Item 9A of the Company’s Annual Report on Form 10-K for the year ended December 31, 2012, as filed with the Securities and Exchange Commission (the “Commission”) on May 2, 2013 (the “2012 Form 10-K”), there were no “reportable events,” as defined in Item 304(a)(1)(v) of Regulation S-K that occurred during the Company’s two most recent fiscal years or during the subsequent interim period through June 19, 2013. The material weaknesses in internal control over financial reporting identified in the 2012 Form 10-K related to (1) a sufficient complement of accounting and financial reporting resources; (2) accounting for certain transactions for oil and gas unproved properties; (3) accounting for income taxes; (4) appropriate segregation of duties related to certain system access rights and the recording and review of journal entries; (5) preparation and review of certain classification and disclosure matters impacting the financial statements and related notes; and (6) significant and complex debt and equity transactions. Because of these weaknesses, the Company’s management concluded, as reported in the 2012 Form 10-K, that the Company did not maintain effective internal control over financial reporting as of December 31, 2012. PwC, in its attestation report in the 2012 Form 10-K also reported that, in its opinion, the Company did not maintain in all material respects, effective internal control over financial reporting as of December 31, 2012. The Audit Committee has discussed these matters with PwC, and the Company has authorized PwC to respond fully to any inquiries by UHY.

1

The Company has provided PwC with a copy of this Current Report on Form 8-K (this “Form 8-K”) and requested that PwC furnish the Company with a letter addressed to the Commission stating whether PwC agrees with the statements made by the Company herein. A copy of PwC’s response letter is included as Exhibit 16.1 to this Form 8-K.

During the fiscal years ended December 31, 2011 and 2012 and the subsequent interim period through the date of UHY’s engagement, neither the Company nor anyone acting on its behalf consulted UHY with respect to either (i) the application of accounting principles to a specified transaction, either completed or proposed, or the type of audit opinion that might be rendered on the Company’s consolidated financial statements, and no written report or oral advice was provided by UHY to the Company that UHY concluded was an important factor considered by the Company in reaching a decision as to the accounting, auditing, or financial reporting issue; or (ii) any matter that was the subject of either a disagreement (as defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions to such item) or a reportable event (as described in Item 304(a)(1)(v) of Regulation S-K).

Item 9.01 Financial Statements and Exhibits

(d) Exhibits

2

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