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 26, 2015

Portola Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (650) 246-7300

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

¨     Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨     Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨     Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨     Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

On January 26, 2015, Robert Califf, M.D., submitted his resignation as an independent director of the Board of Directors of Portola Pharmaceuticals, Inc. (the “Company”), effective immediately. Dr. Califf was serving as a member of the Nominating and Corporate Governance Committee of the Board of Directors prior to his resignation. Dr. Califf resigned to accept a position as the Deputy Commissioner for Medical Products and Tobacco at the Food and Drug Administration. Dr. Califf’s resignation was not the result of any disagreement with Portola on any matter relating to its operations, policies, or practices. Effective as of his resignation, Dr. Califf is no longer a member of the Board of Directors or any of its committees.

Portola thanks Dr. Califf for his contributions to the Board of Directors.

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.