Harrison Township is a township in Allegheny County in the U.S. state of Pennsylvania. The population was 10,169 at the 2020 census. Pennsylvania Route 28 passes through Harrison Township, connecting Kittanning to the northeast and Pittsburgh to the southwest. Allegheny Technologies has extensive steel mill facilities in Harrison Township, including its Allegheny Ludlum Brackenridge Works. Harrison Township is located at the far northeast corner of Allegheny County. Its northern border is the Butler County line and the Allegheny River forms the township's eastern boundary with Westmoreland County. Its northeast corner also touches Armstrong County.

Pennsylvania Route 28 is a major state highway, which runs for 98 miles (158 km) from Anderson Street in Pittsburgh to U.S. Route 219 (US 219) in Brockway in Pennsylvania in the United States.