Wilmerding is a borough in Allegheny County, Pennsylvania, United States. The population was 2,190 at the 2010 census. It is located 12 miles (19 km) southeast of Pittsburgh. At the start of the twentieth century, it had extensive foundries and machine shops of the Westinghouse Air Brake Company. Wilmerding is adjacent to the borough of Turtle Creek, which takes its name from a small stream that flows past both places.