Petersburg is a borough in Huntingdon County, Pennsylvania, United States.

It was a stop on the former Pennsylvania Railroad Main Line between Tyrone and Huntingdon and the junction point for the Petersburg Branch.

Huntingdon, the county seat, is 9 miles (14 km) to the south via local roads.

According to the United States Census Bureau, the borough has a total area of 0.33 square miles (0.86 km2), all land.

The racial makeup of the borough was 99.56% White, 0.22% Native American, and 0.22% from two or more races.