[2] It is part of the Johnstown, Pennsylvania, Metropolitan Statistical Area.

According to the United States Census Bureau, the township has a total area of 29.4 square miles (76.0 km2), all land.

The borough of Wellersburg is located at the extreme southern end of the township, along its border with Maryland.

Pennsylvania Route 160 passes through Southampton Township as it runs north from Wellersburg & the Maryland border and then progresses west into Larimer Township.

Savage Mountain runs along the western edge of the township.