Exhibit 8.1

City Office REIT, Inc.

1075 West Georgia Street, Suite 2600

Vancouver, BC V6E 3C9

City Office REIT, Inc.

Qualification as

Real Estate Investment Trust

Ladies and Gentlemen:

We have acted as tax counsel to City Office REIT, Inc., a Maryland corporation (the “Company”), in connection with the preparation of a registration statement on Form S-3 (the “Registration Statement”), as filed with the Securities and Exchange Commission on May 5, 2015 (File No. 333-203882), with respect to the offer and sale from time-to-time of up to an aggregate of $500,000,000 of shares of common stock, par value $0.01 per share, of the Company (the “Common Stock”), shares of preferred stock, par value $0.01 per share, of the Company (the “Preferred Stock”), debt securities of the Company, warrants entitling the holders to purchase Common Stock or Preferred Stock, and units comprising two or more of the preceding securities of the Company, and the offer and sale of up to 5,750,000 shares of Common Stock, pursuant to a preliminary prospectus supplement filed on January 9, 2017 and a final prospectus supplement filed on January 11, 2017 (together, the “Prospectus Supplement”), as part of the Registration Statement. You have requested our opinion regarding certain U.S. federal income tax matters.

In giving this opinion letter, we have examined the following:

ATLANTA    AUSTIN    BANGKOK    BEIJING    BRUSSELS     CHARLOTTE    DALLAS    HOUSTON    LONDON    LOS ANGELES

McLEAN    MIAMI    NEW YORK    NORFOLK    RALEIGH    RICHMOND    SAN FRANCISCO    TOKYO    WASHINGTON

www.hunton.com

City Office REIT, Inc.

January 12, 2017

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In connection with the opinions rendered below, we have assumed, with your consent, that:

In connection with the opinions rendered below, we also have relied upon the correctness of the factual representations contained in the Officer’s Certificate and the factual matters discussed in the Prospectus and the Prospectus Supplement that relate to the Company’s status as a REIT. We are not aware of any facts that are inconsistent with the representations contained in the Officer’s Certificate.

Based solely on the documents and assumptions set forth above, the representations set forth in the Officer’s Certificate, and the factual matters discussed in the Prospectus under the caption “Material Federal Income Tax Considerations” and in the Prospectus Supplement under the caption “Additional Material Federal Income Tax Considerations” (which are incorporated herein by reference), we are of the opinion that:

City Office REIT, Inc.

January 12, 2017

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(a)    the Company qualified to be taxed as a REIT pursuant to sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “Code”) for its taxable years ended December 31, 2014 through December 31, 2016, and the Company’s organization and current and proposed method of operation will enable it to continue to qualify as a REIT under the Code for its taxable year ending December 31, 2017 and thereafter; and

(b)    the descriptions of the law and the legal conclusions contained in the Prospectus under the caption “Material Federal Income Tax Considerations” and in the Prospectus Supplement under the caption “Additional Material Federal Income Tax Considerations” are correct in all material respects.

We will not review on a continuing basis the Company’s compliance with the documents or assumptions set forth above, or the representations set forth in the Officer’s Certificate. Accordingly, no assurance can be given that the actual results of the Company’s operations for any given taxable year will satisfy the requirements for qualification and taxation as a REIT. Although we have made such inquiries and performed such investigations as we have deemed necessary to fulfill our professional responsibilities as counsel, we have not undertaken an independent investigation of all the facts referred to in this opinion letter or the Officer’s Certificate. In particular, we note that the Company has engaged in transactions in connection with which we have not provided legal advice and may not have reviewed. Moreover, we note that we did not represent the Company prior to March 2015.

The foregoing opinions are based on current provisions of the Code and the Treasury regulations thereunder (the “Regulations”), published administrative interpretations thereof, and published court decisions. The Internal Revenue Service has not issued Regulations or administrative interpretations with respect to various provisions of the Code relating to REIT qualification. No assurance can be given that the law will not change in a way that will prevent the Company from qualifying as a REIT.

The foregoing opinions are limited to the U.S. federal income tax matters addressed herein, and no other opinions are rendered with respect to other U.S. federal tax matters or to any issues arising under the tax laws of any other country, or any state or locality. We undertake no obligation to update the opinions expressed herein after the date of this letter. This opinion letter speaks only as of the date hereof. Except as provided in the next paragraph, this opinion letter may not be distributed, quoted in whole or in part or otherwise reproduced in any document, or filed with any governmental agency without our express written consent.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement. We also consent to the references to Hunton & Williams LLP under the

City Office REIT, Inc.

January 12, 2017

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caption “Legal Matters” in the Prospectus Supplement. In giving consent, we do not admit that we are in the category of persons whose consent is required by Section 7 of the Securities Act of 1933, as amended, or the rules and regulations promulgated thereunder by the Securities and Exchange Commission.