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): April 24, 2012

WESTERN ALLIANCE BANCORPORATION

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (602) 389-3500

(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 April 24, 2012, Western Alliance Bancorporation (the “Company”) held its Annual Meeting of Stockholders (the “Annual Meeting”). The total number of shares of the Company’s common stock, par value of $0.0001 per share, voted in person or by proxy at the Annual Meeting was 74,947,407, representing approximately 90% of the 83,132,092 shares outstanding and entitled to vote at the Annual Meeting. All matters voted upon at the Annual Meeting were approved with the required votes. The matters that were voted upon at the Annual Meeting, and the number of votes cast for, against or withheld, as well as the number of the number of abstentions and broker non-votes, as to each such matter, where applicable, are set forth below.

The Company’s stockholders elected five Class I directors to each serve for a three-year term expiring in 2015. The voting results were as follows:

The Company’s stockholders approved an amendment to the 2005 Stock Incentive Plan that (i) increased by 2,000,000 the maximum number of shares available for issuance thereunder; (ii) increased the maximum number of shares of Stock that can be awarded to any person eligible for an award thereunder to 300,000 per calendar year; and (iii) provides for additional business criteria upon which performance-based awards may be based thereunder. The voting results were as follows:

The Company’s stockholders approved, on a non-binding advisory basis, executive compensation. The voting results were as follows:

The Company’s stockholders approved, on a non-binding advisory basis, holding an annual vote on executive compensation. In light of such vote, the Company will include a stockholder vote on the compensation of executives in its proxy materials annually until the next required vote on the frequency of stockholder votes on the compensation of executives. The voting results were as follows:

The Company’s stockholders ratified the appointment of McGladrey & Pullen, LLP as the Company’s independent auditors for the fiscal year ending December 31, 2012. The voting results were as follows:

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.