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): December 18, 2012

Health Net, Inc.

(Exact Name of Registrant as Specified in Charter)

Registrant’s telephone number, including area code: (818) 676-6000

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:

On December 18, 2012, Health Net, Inc. (the “Company”) issued a press release announcing the Company’s earnings guidance for the full year 2013. The press release is attached hereto as Exhibit 99.1 and hereby incorporated into this Item 7.01 by reference.

The information in this Item 7.01 shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any Company filing under the Securities Act of 1933 or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

CAUTIONARY STATEMENTS: The Company and its representatives may from time to time make written and oral forward-looking statements within the meaning of the Private Securities Litigation Reform Act (“PSLRA”) of 1995, including statements in this and other reports, in presentations, press releases, filings with the Securities and Exchange Commission (“SEC”), reports to stockholders and in meetings with investors and analysts. All statements in this report, other than statements of historical information provided herein, including the guidance for future periods and the assumptions underlying such projections, may be deemed to be forward-looking statements and as such are intended to be covered by the safe harbor for “forward-looking statements” provided by PSLRA. These statements are based on management’s analysis, judgment, belief and expectation only as of the date hereof, and are subject to changes in circumstances and a number of risks and uncertainties. Without limiting the foregoing, the guidance as to expected future period results and statements including the words “believes,” “anticipates,” “plans,” “expects,” “may,” “should,” “could,” “estimate,” “intend,” “feels,” “will,” “projects” and other similar expressions are intended to identify forward-looking statements. Actual results could differ materially from those expressed in, or implied or projected by the forward-looking information and statements due to, among other things, health care reform and other increased government participation in and regulation of health benefits and managed care operations, including the ultimate impact of the Affordable Care Act, which could materially adversely affect the Company’s financial condition, results of operations and cash flows through, among other things, reduced revenues, new taxes, expanded liability, and increased costs (including medical, administrative, technology or other costs), or require changes to the ways in which the Company does business; rising health care costs; continued slow economic growth or a further decline in the economy; negative prior period claims reserve developments; trends in medical care ratios; membership declines; unexpected utilization patterns or unexpectedly severe or widespread illnesses; rate cuts and other risks and uncertainties affecting the Company’s Medicare or Medicaid businesses; the Company’s ability to successfully participate in the dual eligibles pilot programs; litigation costs; regulatory issues with federal and state agencies including, but not limited to, the California Department of Managed Health Care, the Centers for Medicare & Medicaid Services, the Office of Civil Rights of the U.S. Department of Health and Human Services and state departments of insurance; operational issues; failure to effectively oversee the Company’s third-party vendors; noncompliance by the Company or the Company’s business associates with any privacy laws or any security breach involving the misappropriation, loss or other unauthorized use or disclosure of confidential information; liabilities incurred in connection with the Company’s divested operations; impairment of the Company’s goodwill or other intangible assets; investment portfolio impairment charges; volatility in the financial

markets; and general business and market conditions. Additional factors that could cause actual results to differ materially from those reflected in the forward-looking statements include, but are not limited to, the risks discussed in the “Risk Factors” section included within the Company’s most recent Annual Report on Form 10-K and subsequent Quarterly Reports on Form 10-Q filed with the SEC, and the other risks discussed in the Company’s filings with the SEC. Readers are cautioned not to place undue reliance on these forward-looking statements. Except as may be required by law, the Company undertakes no obligation to address or publicly update any of its guidance, the assessment of the underlying assumptions or forward-looking statements to reflect events or circumstances that arise after the date of this report.

Exhibit Index

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.