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 23, 2017

OCULAR THERAPEUTIX, INC.

(Exact Name of Company as Specified in Charter)

34 Crosby Drive, Suite 105

Bedford, MA 01730

(Address of Principal Executive Offices) (Zip Code)

Company’s telephone number, including area code: (781) 357-4000

(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 1.01. Entry into a Material Definitive Agreement.

Underwriting Agreement

On January 23, 2017, Ocular Theapeutix, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Cantor Fitzgerald & Co. (the “Underwriter”), to issue and sell to the Underwriter 3,571,429 shares of the Company’s common stock, par value $0.0001 per share (the “Shares”), in an underwritten public offering. The underwriter agreed to purchase the Shares from the Company at a price of $6.57 per share. The Company estimates that the net proceeds from the offering, after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company, will be approximately $23.2 million.

The Shares will be issued pursuant to an effective shelf registration statement on Form S-3 (File No. 333-210777). A prospectus supplement relating to the offering has been filed with the Securities and Exchange Commission. The closing of the offering is expected to take place on January 27, 2017, subject to customary closing conditions.

A copy of the Underwriting Agreement is attached as Exhibit 1.1 hereto and is incorporated herein by reference. The foregoing description of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to such exhibit.

A copy of the legal opinion and consent of Wilmer Cutler Pickering Hale and Dorr LLP relating to the Common Stock issued and sold in the offering is attached as Exhibit 5.1 hereto.

Item 8.01. Other Events.

The full text of the press release announcing the proposed underwritten public offering on January 23, 2017 and the full text of the press release announcing the pricing of the underwritten public offering on January 24, 2017 are attached as Exhibits 99.1 and 99.2 hereto and are incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

(d)    Exhibits.

See Exhibit Index attached hereto.

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.

EXHIBIT INDEX