Exhibit 99.1

CyrusOne Inc. Announces Public Offering of Common Stock

DALLAS ¾ August 9, 2016 ¾ CyrusOne Inc. (NASDAQ: CONE) (“CyrusOne”) announced today that it has commenced the public offering of 6,800,000 shares of its common stock, of which 3,400,000 shares will be offered directly by CyrusOne, and 3,400,000 shares will be offered, at the request of CyrusOne, by the Forward Purchaser (as defined below) or its affiliate in connection with the forward sale agreement described below.  The underwriters will be granted an option to purchase up to 1,020,000 additional shares of common stock from the Forward Purchaser or its affiliate.

Goldman, Sachs & Co. and Morgan Stanley are acting as joint-bookrunners for the offering.

In connection with the offering of CyrusOne’s common stock, CyrusOne expects to enter into a forward sale agreement with Goldman, Sachs & Co. (who is referred to in such capacity as the “Forward Purchaser”), with respect to 3,400,000 shares of its common stock covered by the offering. The Forward Purchaser or its affiliate is expected to borrow from third parties and sell to the public through the underwriters 3,400,000 shares of CyrusOne’s common stock.  In addition, if the underwriters’ option to purchase additional shares is exercised, such additional shares of common stock are expected to be sold by the Forward Purchaser or its affiliate to the underwriters, in which case CyrusOne will enter into one or more additional forward sale agreements with the Forward Purchaser in respect of the number of additional shares of common stock that are subject to the option being exercised.

Pursuant to the terms of the forward sale agreements, and subject to CyrusOne’s right to elect cash or net share settlement under the forward sale agreements, CyrusOne intends to issue and sell, upon physical settlement of such forward sale agreements, 3,400,000 shares of its common stock to the Forward Purchaser (or 4,420,000 shares, if the underwriters’ option to purchase additional shares is exercised in full) in exchange for cash proceeds per share equal to the applicable forward sale price, which will initially be the public offering price, less underwriting discounts and commissions, and will be subject to certain adjustments as provided in the applicable forward sale agreement. CyrusOne expects to physically settle the forward sale agreement (and additional forward sale agreements, if any) in full, which settlement or settlements will occur by August 1, 2017.

CyrusOne will receive proceeds from the sale of 3,400,000 shares of its common stock offered by it in the offering, but will not initially receive any proceeds from the sale of 3,400,000 shares of its common stock (or 4,420,000 shares, if the underwriters’ option to purchase additional shares is exercised in full) offered by the Forward Purchaser or its affiliate to the underwriters, except in certain circumstances described in the prospectus supplement relating to the offering. CyrusOne expects to contribute, directly and indirectly, the net proceeds from the offering to its operating partnership, CyrusOne LP (the “Operating Partnership”), in exchange for an equivalent number of newly issued common units of limited partnership interests in the Operating Partnership. The Operating Partnership is expected to use such proceeds to fund growth capital expenditures related to recently signed leases, to repay borrowings under its senior unsecured revolving credit facility, and for general corporate purposes, which may include funding future acquisitions, investments or capital expenditures.

The shares are being offered pursuant to an effective shelf registration statement filed with the Securities and Exchange Commission (“SEC”). The offering will be made only by means of a prospectus supplement and accompanying prospectus. The preliminary prospectus supplement and accompanying prospectus related to the offering has been filed with the SEC and is available on the SEC’s website at http://www.sec.gov. A copy of the preliminary prospectus supplement and final prospectus supplement, when available, along with the accompanying prospectus related to the offering may be obtained by contacting Goldman, Sachs & Co., 200 West Street, New York, New York 10282, Attention: Prospectus Department, by calling (866) 471-2526 or by emailing prospectus-ny@ny.email.gs.com; or Morgan Stanley & Co. LLC, 180 Varick Street, 2nd Floor, New York, New York 10014, Attention: Prospectus Department.

This news release shall not constitute an offer to sell, or the solicitation of an offer to buy, these securities, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

About CyrusOne

CyrusOne (NASDAQ: CONE) specializes in highly reliable enterprise-class, carrier-neutral data center properties. CyrusOne provides mission-critical data center facilities that protect and ensure the continued operation of IT infrastructure for more than 950 customers, including nine of the Fortune 20 and 177 of the Fortune 1000 companies.

CyrusOne’s data center offerings provide the flexibility, reliability, and security that enterprise customers require and are delivered through a tailored, customer service-focused platform designed to foster long-term relationships. CyrusOne is committed to full transparency in communication, management, and service delivery throughout its 35 data centers worldwide.

Safe Harbor

This release contains forward-looking statements regarding future events and CyrusOne’s future results that are subject to the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995. All statements, other than statements of historical facts, are statements that could be deemed forward-looking statements. These statements are based on current expectations, estimates, forecasts, and projections about the industries in which CyrusOne operates and the beliefs and assumptions of its management. Words such as “expects,” “anticipates,” “predicts,” “projects,” “intends,” “plans,” “believes,” “seeks,” “estimates,” “continues,” “endeavors,” “strives,” “may,” variations of such words and similar expressions are intended to identify such forward-looking statements. In addition, any statements that refer to projections of CyrusOne’s future financial performance, its anticipated growth and trends in its businesses, and other characterizations of future events or circumstances are forward-looking statements.

Readers are cautioned these forward-looking statements are based on current expectations and assumptions that are subject to risks and uncertainties, which could cause CyrusOne’s actual results to differ materially and adversely from those reflected in the forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed in this release and those discussed in other documents CyrusOne files with the SEC. More information on potential risks and uncertainties is available in CyrusOne’s recent filings with the SEC, including CyrusOne’s Form 10-K report, Form 10-Q reports, and Form 8-K reports and its registration statement (No. 333-211114 on Form S-3). Actual results may differ materially and adversely from those expressed in any forward-looking statements. CyrusOne undertakes no obligation to revise or update any forward-looking statements for any reason.

Source: CyrusOne Inc.

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Investor Relations

Michael Schafer

972-350-0060

investorrelations@cyrusone.com

Media

Jacob Smith

513-671-3811

cyrusone@gyro.com