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): May 9, 2013

EXPRESS SCRIPTS HOLDING COMPANY

(Exact Name of Registrant as Specified in its Charter)

Registrant’s telephone number including area code: 314-996-0900

No change since last report

(Former Name or 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):

Express Scripts Holding Company (the “Company”) held its annual meeting of stockholders (the “Annual Meeting”) at the Company’s principal executive offices on Thursday, May 9, 2013. Of the 819,963,709 shares outstanding and entitled to vote, 708,635,265 shares were represented at the meeting, or an 86.42% quorum. The final results for each of the matters submitted to a vote of stockholders at the Annual Meeting are as follows:

Proposal 1. Election of Directors. All of the nominees nominated by the Board of Directors for director were elected to serve until the next Annual Meeting or until their respective successors are elected and qualified, by the votes set forth in the table below.

Proposal 2. The appointment of PricewaterhouseCoopers LLP as the Company’s independent registered public accountants for 2013 was ratified by the stockholders, by the votes set forth in the table below.

Proposal 3. The stockholders approved, on a non-binding basis, executive compensation, by the votes set forth in the table below.

SIGNATURE

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 thereunto duly authorized.