Brentwood is a borough in Allegheny County, Pennsylvania, United States and is part of the Pittsburgh Metro Area. The population was 10,466 at the 2000 census.
Brentwood is located at 40°22′28″N 79°58′34″W / 40.37444°N 79.97611°W / 40.37444; -79.97611 (40.374469, -79.976179). According to the United States Census Bureau, the borough has a total area of 1.5 square miles (3.8 km²), all of it land.
The borough is located on the Allegheny Plateau, 5 miles south the confluence of the Allegheny River from the Northeast and Monongahela River from the Southeast form the Ohio River.