Exhibit 5.1

425 MARKET STREET SAN FRANCISCO CALIFORNIA 94105-2482   TELEPHONE: 415.268.7000 FACSIMILE: 415.268.7522   WWW.MOFO.COM MORRISON & FOERSTER LLP   NEW YORK, SAN FRANCISCO, LOS ANGELES, PALO ALTO, SAN DIEGO, WASHINGTON, D.C.   NORTHERN VIRGINIA, DENVER, SACRAMENTO, WALNUT CREEK   TOKYO, LONDON, BRUSSELS, BEIJING, SHANGHAI, HONG KONG

September 19, 2013

RE/MAX Holdings, Inc.

5075 South Syracuse Street

Denver, Colorado 802375

Re: Registration Statement on Form S-1

Ladies and Gentlemen:

We are acting as counsel to RE/MAX Holdings, Inc., a Delaware corporation (the “Company”), in connection with the registration of 11,500,000 shares of the Company’s Class A Common Stock, par value $0.0001 per share (the “Common Stock”), pursuant to a Registration Statement on Form S-1, as amended (the “Registration Statement”), filed with the Securities and Exchange Commission under the Securities Act of 1933, as amended, covering the offering and sale of 10,000,000 shares of Common Stock, and, if exercised, the offering and sale by the Company of up to 1,500,000 shares of Common Stock subject to the underwriters’ option to purchase additional shares, as described in the Registration Statement (collectively, the “Shares”).

As counsel for the Company, we have examined originals or copies, certified or otherwise identified to our satisfaction, of such documents, corporate records, certificates of public officials and other instruments as we have deemed necessary for the purposes of rendering this opinion and we are familiar with the proceedings taken and proposed to be taken by the Company in connection with the authorization, issuance and sale of the Shares. In our examination, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals and the conformity with the originals of all documents submitted to us as copies.

Based upon the foregoing, we are of the opinion that the Shares will be duly and validly authorized and upon issuance, delivery and payment therefor in the manner contemplated by the Underwriting Agreement referred to in the Prospectus forming a part of the Registration Statement, will be validly issued, fully paid and nonassessable

We consent to the use of this opinion as an exhibit to the Registration Statement, and we consent to the reference of our name under the caption “Legal Matters” in the Prospectus forming a part of the Registration Statement. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act.

Very truly yours,

/s/ Morrison & Foerster LLP