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): August 19, 2013

ZILLOW, INC.

(Exact name of registrant as specified in its charter)

(206) 470-7000

(Registrant’s telephone number, including area code)

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 August 19, 2013, Zillow, Inc. (“Zillow” or the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with the several underwriters named in the Underwriting Agreement (the “Underwriters”) for which Citigroup Global Markets Inc. is acting as representative, and the selling shareholders listed on Schedule II thereto (the “Selling Shareholders”), relating to an underwritten public offering of 5,023,486 shares (the “Shares”) of the Company’s Class A common stock, par value $0.0001 per share (the “Common Stock”), of which 2,523,486 shares are being sold by the Selling Shareholders and 2,500,000 shares are being sold by the Company. The offering price to the public is $82.00 per share, and the Underwriters have agreed to purchase the Shares from the Company and the Selling Shareholders pursuant to the Underwriting Agreement at a price of $78.31 per share. Under the terms of the Underwriting Agreement, the Company granted the Underwriters an option, exercisable for 30 days, to purchase up to an additional 753,522 shares of Common Stock (the “Additional Shares”), which was exercised in full by the Underwriters on August 22, 2013.

The Shares and the Additional Shares will be issued pursuant to an automatic shelf registration statement on Form S-3 (the “Registration Statement”) that the Company filed with the Securities and Exchange Commission (the “SEC”) on August 19, 2013, which Registration Statement became effective upon filing (File No. 333-190700). A prospectus supplement relating to the offering has been filed with the SEC. The closing of the offering and delivery of the Shares and the Additional Shares are expected to take place on August 23, 2013, subject to the satisfaction of customary closing conditions.

The Underwriting Agreement is filed as Exhibit 1.1 to this Current Report on Form 8-K, and such document is incorporated herein by reference. The foregoing is only a brief description of the material terms of the Underwriting Agreement, does not purport to be a complete description of the rights and obligations of the parties thereunder and is qualified in its entirety by reference to such Underwriting Agreement.

The legal opinion and consent of Perkins Coie LLP relating to the Shares and the Additional Shares is filed as Exhibit 5.1 to this Current Report on Form 8-K, and such document is incorporated herein by reference. Certain information relating to Part II, Item 14 “Other Expenses of Issuance and Distribution” of the Registration Statement is filed as Exhibit 99.1 to this Current Report on Form 8-K.

On August 19, 2013, Zillow issued a press release announcing the pricing of the Shares described in Item 1.01 above. The press release is furnished as Exhibit 99.2 to this Current Report on Form 8-K.

(d) Exhibits.

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.

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