Prince George's County is located in the U.S. state of Maryland immediately north, east, and south of Washington, D.C. It is home to the United States Department of Agriculture's Henry A. Wallace Beltsville Agricultural Research Center, the National Aeronautics and Space Administration's Goddard Space Flight Center, Andrews Air Force Base, the National Archives and Records Administration's College Park, Maryland facility, the University of Maryland's flagship College Park campus, Six Flags America and Six Flags Hurricane Harbor, FedEx Field (home of the Washington Redskins) and the soon-to-be-completed National Harbor, which its developers, Peterson Companies and Gaylord Entertainment Company, bills the largest single mixed-use project and combined convention center–hotel complex on the East Coast. The project is worth more than $2.1 Billion.

The county was named for Prince George of Denmark, the brother of King Christian V of Denmark and Norway, and husband of Queen Anne of Great Britain. Its county seat is Upper Marlboro.