Watsontown is a borough in Northumberland County, Pennsylvania, United States. The population was 2,351 at the 2010 census. It was named for John Watson, an early settler.
Land in the Watsontown area was first purchased by John Watson in 1792. The borough's post office was opened in 1828. There was a racetrack in Watsontown from 1830 to 1840. Railroad tracks first reached the borough in 1854. A sawmill was built in the area in 1856. Watsontown was a part of Turbot Township until its incorporation in 1867.
Watsontown is located at 41°5′7″N 76°51′48″W (41.085319, -76.863325). According to the United States Census Bureau, the borough has a total area of 0.9 square miles (2.3 km2), of which, 0.7 square miles (1.8 km2) of it is land and 0.2 square miles (0.52 km2) of it (24.47%) is water.