Rigas was appointed to the General Services Administration (GSA) during the administration of President George W. Bush.[4] He was an associate administrator for the agency and held the positions of senior advisor and deputy administrator.[4] During this time, he was part of an effort to improve the level of government contracting to woman- and veteran-owned businesses.[6]
After his service in the Bush administration, Rigas worked for several Republican organizations.[7] He was an official for the Massachusetts Republican Party and worked for The Heritage Foundation, a conservative think tank.[6] Following that, he worked for the Massachusetts Department of Veterans' Services as chief of staff.[6]
In July 2017, Rigas was nominated by President Donald Trump to serve as deputy director of the United States Office of Personnel Management (OPM).[8] On March 7, 2018, he was unanimously confirmed by the Senate to serve in the position, with Rigas thus serving under the OPM's director, Jeff Tien Han Pon.[8][9] On March 18, 2020, Rigas became the acting director of the OPM after the resignation of the then-director, Dale Cabaniss.[10] In this role, he thus became head of the agency in charge for managing "human resources, talent recruitment, development, and policy" for the employees of the federal government.[5]