Exhibit 32.1

SECTION 1350 CERTIFICATIONS

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Orion Group Holdings, Inc. (the “Company”) on Form 10-Q for the quarter ended June 30, 2018 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), we, Mark R. Stauffer and Christopher J. DeAlmeida, Chief Executive Officer and Chief Financial Officer , respectively, of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that to our knowledge:

1. The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and result of operations of the Company.

By:	/s/ Mark R. Stauffer
August 3, 2018	Mark R. Stauffer
	Chief Executive Officer
By:	/s/ Christopher J. DeAlmeida
August 3, 2018	Christopher J. DeAlmeida
	Executive Vice President and Chief Financial Officer