Kilroy Realty Corporation, a Maryland corporation (the “Company”) – Registration of up to 5,750,000 shares (the “Shares”) of common stock, par value one cent ($0.01) per share (the “Common Stock”), of the Company to be sold to the public (the “Offering”) pursuant to the Registration Statement on Form S-3 (Registration Nos. 333-213864 and 333-213864-01) filed with the United States Securities and Exchange Commission (the “Commission”) on September 29, 2016 (the “Registration Statement”)

the corporate charter of the Company (the “Charter”) consisting of Articles of Amendment and Restatement filed with the State Department of Assessments and Taxation of Maryland (the “Department”) on January 21, 1997, Articles Supplementary filed with the Department on February 6, 1998, Articles Supplementary filed with the Department on April 20, 1998, Articles Supplementary filed with the Department on October 15, 1998, Articles Supplementary filed with the Department on November 25, 1998, Certificate of Correction filed with the Department on March 4, 1999, Articles Supplementary filed with the Department on December 10, 1999, Articles Supplementary filed with the Department on December 30,

the Second Amended and Restated Bylaws of the Company, adopted as of December 11, 2008, as amended by the Amendment No. 1 to the Second Amended and Restated Bylaws, adopted as of May 27, 2009, and the Amendment No. 2 to the Second Amended and Restated Bylaws, adopted as of May 22, 2014, as amended and restated by the Third Amended and Restated Bylaws of the Company, adopted as of December 9, 2014, as further amended and restated by the Fourth Amended and Restated Bylaws of the Company, adopted as of February 23, 2016 and as further amended and restated by the Fifth Amended and Restated Bylaws of the Company, adopted as of January 30, 2017 (collectively, the “Bylaws”);

the Written Organizational Action of the Board of Directors of the Company, dated as of September 13, 1996 (the “Organizational Minutes”);

resolutions adopted by the Board of Directors of the Company, or a committee thereof, December 12, 2017 and August 8, 2018 (collectively, the “Directors’ Resolutions”);

the Registration Statement, including all amendments thereto if any, filed by the Company with the Commission under the Act, the related preliminary prospectus supplement, dated August 8, 2018, the related final prospectus supplement, dated August 8, 2018, and the final base prospectus, dated September 29, 2016, and;

a status certificate of the Department, dated as of a recent date, to the effect that the Company is duly incorporated and existing under the laws of the State of Maryland and is duly authorized to transact business in the State of Maryland;

a fully executed copy of the Underwriting Agreement dated as of August 8, 2018 (the “Underwriting Agreement”), by and among the Company, Kilroy Realty, L.P., a Delaware limited partnership, and Barclays Capital Inc. and Citigroup Global Markets Inc., (“Citigroup”) for themselves and as representatives of the several underwriters named in “Schedule A” of the Underwriting Agreement and Barclays Bank PLC and Citigroup, as Forward Sellers (as defined therein);

a certificate of Tyler H. Rose, Executive Vice President, Chief Financial Officer and Secretary of the Company and Michelle Ngo, Senior Vice President and Treasurer of the Company, dated as of the date hereof (the “Officers’ Certificate”), to the effect that, among other things, the Charter, the Bylaws, the Organizational Minutes and the Directors’ Resolutions are true, correct and complete, and that the Charter, the Bylaws, the Organizational Minutes and the Directors’ Resolutions have not been rescinded or modified and are in full force and effect as of the date of the Officers’ Certificate and certifying as to the form, approval, execution and delivery of the Underwriting Agreement; and

such other laws, records, documents, certificates, opinions and instruments as we have deemed necessary and appropriate to render the opinions set forth in this letter, subject to the limitations, assumptions, and qualifications noted below.

each person executing any of the Documents on behalf of a party (other than the Company) is duly authorized to do so;

each natural person executing any of the Documents is legally competent to do so;

any of the Documents submitted to us as originals are authentic; the form and content of any Documents submitted to us as unexecuted drafts do not, and will not, differ in any respect relevant to this opinion from the form and content of such documents as executed and delivered; any of the Documents submitted to us as certified, facsimile or photostatic copies conform to the original documents; all signatures on all Documents are genuine; all public records reviewed or relied upon by us

none of the Shares will be issued or transferred in violation of the provisions of Article IV of Article SECOND of the Articles of Restatement relating to restrictions on ownership and transfer of capital stock of the Company.

The Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Maryland.

The Shares to be issued in the Offering have been duly authorized for issuance by all necessary corporate action on the part of the Company, and when such Shares are issued and delivered by the Company in exchange for payment of the consideration therefor, as provided in, and in accordance with, the Underwriting Agreement and the Directors’ Resolutions, such Shares will be validly issued, fully paid and non-assessable.