Exhibit 5.1

ORRICK, HERRINGTON & SUTCLIFFE LLP THE ORRICK BUILDING 405 HOWARD STREET SAN FRANCISCO, CALIFORNIA 94105-2669   tel +1-415-773-5700 fax +1-415-773-5759   WWW.ORRICK.COM

April 13, 2016

Ooma, Inc.

1880 Embarcadero Road

Palo Alto, CA 94303

Re: Registration Statement on Form S-8

Ladies and Gentlemen:

We are acting as counsel for Ooma, Inc., a Delaware corporation (the “Company”), in connection with the preparation and filing with the Securities and Exchange Commission (the “Commission”) of the Company’s Registration Statement on Form S-8 (the “Registration Statement”), under the Securities Act of 1933, as amended (the “Securities Act”), relating to the registration of 854,483 shares of the Company’s common stock, par value $0.0001 per share (the “Common Stock”), reserved for issuance pursuant to the Company’s 2015 Equity Incentive Plan and 341,793 shares of Common Stock reserved for issuance pursuant to the Company’s 2015 Employee Stock Purchase Plan (which plans are referred to herein as the “Plans” and which shares of Common Stock are referred to herein as the “Shares”). As your legal counsel, we have reviewed the actions proposed to be taken by you in connection with the issuance and sale of the Shares to be issued under the Plans.

In connection with rendering the opinion set forth below, we have examined and relied upon originals or copies, certified or otherwise identified to our satisfaction, of instruments, documents, and records which we deemed relevant and necessary for the purpose of rendering our opinion set forth below. In such examination, we have assumed the following: (a) the authenticity of original documents and the genuineness of all signatures, (b) the conformity to the originals of all documents submitted to us as copies, and (c) the representations of officers and employees are correct as to questions of fact.

Our opinion herein is limited to the General Corporation Law of the State of Delaware and the federal laws of the United States of America, and we express no opinion as to the effect on the matters covered by this letter of the laws of any other jurisdictions.

Based on the foregoing, and subject to the qualifications stated herein, we are of the opinion that the Shares to be issued pursuant to the terms of the Plans have been duly authorized and, when issued, delivered and paid for in accordance with the terms of the Plans, will be validly issued, fully paid and non-assessable.

Ooma, Inc.

Registration Statement on Form S-8

April 13, 2016

Page 2

We consent to the filing of this opinion as an exhibit to the Registration Statement. In giving such consent, we do not hereby admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the Rules and Regulations of the Commission promulgated thereunder.

Very truly yours,

/s/ Orrick, Herrington & Sutcliffe LLP

ORRICK, HERRINGTON & SUTCLIFFE LLP