Exhibit 99.1

City Office REIT Announces First Quarter 2015 Results

VANCOUVER—May 8, 2015—City Office REIT, Inc. (NYSE: CIO) (the “Company” or “City Office”), today announced its results for the quarter ended March 31, 2015.

First Quarter Highlights

“During the quarter, our focus continued to be on sourcing acquisition opportunities and implementing specific plans to enhance the value of our properties,” commented James Farrar, City Office’s Chief Executive Officer. “Management has been working to extend in-place lease maturities on a long term basis. During the quarter, we successfully concluded the early renewal of Planar Systems, Inc. at our Amberglen property in Portland. This resulted in the extension of 72,000 square feet of space until 2022 at a 20% higher base rental rate. We remain confident that our efforts at other properties will achieve similar favorable results.”

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Financial Results for the First Quarter 2015

Core FFO was $4.0 million or $0.26 per fully diluted share. AFFO was $3.4 million or $0.21 per fully diluted share. Net loss attributable to the Company for the three months ended March 31, 2015 was $0.7 million, or ($0.06) per fully diluted share.

A reconciliation of Core FFO and AFFO to GAAP net income can be found at the bottom of this release.

Portfolio Operations

The Company reported that its total portfolio as of March 31, 2015 contained 2.4 million net rentable square feet and was 93.7% occupied, including recently signed leases not commenced, at the end of the first quarter 2015. Excluding the impact of acquisitions that occurred during the quarter, this represents an approximately 30 basis point increase compared to the end of the prior quarter. City Office’s net operating income (“NOI”) was $7.1 million on a GAAP basis and $7.2 million on a cash basis during the first quarter of 2015.

Leasing Activity

During the first quarter of 2015, the Company commenced 5 new leases for 14,000 square feet and 2 renewals for 9,000 square feet. Early renewals signed in the first quarter totalled 78,000 square feet, taking the total leasing activity in the quarter to 101,000 square feet.

New Leasing – During the first quarter of 2015, the Company signed 21,000 square feet of new leases with a weighted average lease term of 6.7 years at an average rent per square foot of $21.80 and at an average cost of $4.42 per square foot per year.

Renewal Leasing – 2 of 4 expiring leases renewed in the first quarter of 2015. The Company signed 9,000 square feet of renewal leases at an average rent per square foot of $21.32 and at an average cost of $1.81 per square foot per year.

Acquisitions

The Company completed the acquisition of Logan Tower on February 4, 2015 for a purchase price of $10.5 million. Logan Tower is a 69,968 square foot multi-tenant office building that is 95% occupied and located in downtown Denver. The acquisition is anticipated to generate an initial full-year cash net operating income yield of approximately 8.0% based on the purchase price. The purchase was closed all cash and the property was contributed to City Office REIT’s credit facility as additional security.

Subsequent Events

On April 20, 2015, the Company announced that it entered into an Agreement of Purchase and Sale to acquire Superior Pointe in the Denver, Colorado metropolitan area for a purchase price of $25.8 million. Superior Pointe is a 149,006 square foot Class ‘A’ multi-tenant office property that is 90% occupied in the growing Northwest/Boulder submarket. The acquisition is anticipated to generate an initial full-year cash net operating income yield of approximately 7.5% based on the purchase price and the Company’s planned capital improvements. The major conditions to the acquisition have been satisfied and the transaction is anticipated to close in June 2015.

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Capital Structure

As of March 31, 2015, the Company had total outstanding debt of approximately $189.7 million. All of the Company’s outstanding debt is at fixed rates with a weighted average maturity of 6.0 years.

Dividend

On March 19, 2015, the Company’s board of directors declared a cash dividend of $0.235 per share for the three months ended March 31, 2015. The dividend was paid to stockholders and common unitholders on April 17, 2015.

Webcast and Conference Call Details

City Office’s management will hold a conference call at 11:00 am Eastern Time on May 8, 2015.

The webcast will be available under the “Investor Relations” section of the Company’s website at www.cityofficereit.com. The conference call can be accessed by dialing 1-866-262-0919 for domestic callers and 1-412-902-4106 for international callers.

A replay of the call will be available later in the day on May 8, 2015, continuing through 11:59pm Eastern Time on August 6, 2015 and can be accessed by dialing 1-877-344-7529 for domestic callers and 1-412-317-0088 for international callers. The passcode for the replay is 10063537. A replay will also be available for twelve months following the call at “Webcasts & Events” in the “Investor Relations” section of the company’s website.

A supplemental financial package to accompany the discussion of the results will be posted on www.cityofficereit.com under the “Investor Relations” section.

Non-GAAP Financial Measures

FFO, Core FFO and AFFO are supplemental non-GAAP financial measures.

Funds from Operations (“FFO”) – The National Association of Real Estate Investment Trusts (“NAREIT”) states FFO should represent net income or loss (computed in accordance with GAAP) plus real estate related depreciation and amortization (excluding amortization of deferred financing costs) and after adjustments of unconsolidated partnerships and joint ventures, gains or losses on the sale of property and impairments to real estate.

The Company uses FFO as a supplemental performance measure because it believes that FFO is beneficial to investors as a starting point in measuring the Company’s operational performance. We also believe that, as a widely recognized measure of the performance of REITs, FFO will be used by investors as a basis to compare the Company’s operating performance with that of other REITs.

However, because FFO excludes depreciation and amortization and captures neither the changes in the value of the Company’s properties that result from use or market conditions nor the level of capital expenditures and leasing commissions necessary to maintain the operating performance of the Company’s properties, all of which have real economic effects and could materially impact the Company’s results from operations, the utility of FFO as a measure of the Company’s performance is limited. In addition,

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other equity REITs may not calculate FFO in accordance with the NAREIT definition as the Company does, and, accordingly, the Company’s FFO may not be comparable to such other REITs’ FFO. Accordingly, FFO should be considered only as a supplement to net income as a measure of the Company’s performance.

Core Funds from Operations (“Core FFO”) – We calculate Core FFO by using FFO as defined by NAREIT and adjusting for certain other non-core items. We also exclude from our Core FFO calculation acquisition costs, loss on early extinguishment of debt, changes in the fair value of the earn-out and the amortization of stock based compensation.

Adjusted Funds From Operations (“AFFO”) – We compute AFFO by adding to Core FFO the non-cash amortization of deferred financing fees, and non-real estate depreciation, and then subtracting cash paid for recurring tenant improvements, leasing commissions, and capital expenditures, and eliminating the net effect of straight-line rents, deferred market rent and debt fair value amortization. Recurring capital expenditures exclude development / redevelopment activities, capital expenditures planned at acquisition and costs to reposition a property. We exclude first generation leasing costs within the first two years of our initial public offering or acquisition, which are generally to fill vacant space in properties we acquire or were planned at acquisition. We have further excluded all costs associated with tenant improvements, leasing commissions and capital expenditures which were funded by the entity contributing the properties at closing.

Forward-looking Statements

This press release contains “forward looking statements” within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. All statements that are not statements of historical facts are, or may be deemed to be, forward looking statements. These factors include, but are not limited to, the Company’s ability to source and acquire properties on attractive terms, or at all; the Company’s expectations and forecasts of future leasing activity at its current and future properties, and the Company’s ability to accurately model the income yield, capitalization rate, and other financial metrics used to evaluate its properties. These and other material risks are described in the Company’s Annual Report on 10-K for the year ended December 31, 2014 and any other documents filed by the Company from time to time, which are available from the Company and from the SEC, and you should read and understand these risks when evaluating any forward-looking statement. The Company does not have any obligation to publicly update any forward looking statements to reflect subsequent events or circumstances.

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City Office REIT, Inc. and Predecessor

Condensed Consolidated and Combined Balance Sheets

(Unaudited)

(In thousands, except par value and share data)

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City Office REIT, Inc. and Predecessor

Condensed Consolidated and Combined Statements of Operations

(Unaudited)

(In thousands, except per share data)

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City Office REIT, Inc.

Reconciliation of Net Operating Income

(Unaudited)

(In thousands)

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City Office REIT, Inc.

Reconciliation of Net Income to Adjusted Funds from Operations

(Unaudited)

(In thousands, except share and per share data)

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Contact

City Office REIT, Inc.

Anthony Maretic, CFO

+1-604-806-3366

investorrelations@cityofficereit.com

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