UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 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): February 3, 2015

OREXIGEN THERAPEUTICS, INC.

(Exact Name of Registrant as Specified in its Charter)

Registrant’s telephone number, including area code: (858) 875-8600

(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 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

The Compensation Committee (the “Committee”) of the Board of Directors of the Company approved bonuses for the 2014 fiscal year to be awarded to the Company’s named executive officers. Bonus awards were based on the Committee’s evaluation of the Company’s performance as well as each individual named executive officer’s performance during the 2014 year. The evaluations for Mark Booth, Joseph P. Hagan, Dr. Preston Klassen and Heather Turner also included input from Michael Narachi, the Company’s President and Chief Executive Officer.

The Committee had previously established target bonus levels for the named executive officers. The target bonus for all named executive officers, except Mr. Narachi, is equal to 50% of their respective base salaries. The target bonus for Mr. Narachi is equal to 75% of his base salary. The Committee had previously determined that Mr. Narachi’s annual bonus should be based 100% on the Company’s achievement relative to the 2014 corporate goals. The Committee further determined that with respect to each other named executive officer, 60% of their annual bonus should be tied to the Company’s achievement relative to the 2014 corporate goals. The Committee reviewed the Company’s performance against the 2014 corporate goals and determined that the Company had reached 90% of its target corporate goals. Based on all of the above factors, the Committee determined that the total bonuses awarded for the 2014 fiscal year to each named executive officer are as follows:

In addition, the Committee also determined to increase the annual base salaries for the 2015 fiscal year for Mr. Narachi and Dr. Klassen by 3% each and for Mr. Hagan by 4% to $659,844, $390,628 and $394,420, respectively.

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.