Prospect is a borough in Butler County, Pennsylvania, United States.

[4] U.S. Route 422, a limited-access highway, cuts across the northeastern corner of the borough, leading east 11 miles (18 km) to Butler, the county seat, and west 14 miles (23 km) to New Castle.

Moraine State Park, a recreation destination surrounding Lake Arthur, is next to the northwestern border of the borough.

According to the United States Census Bureau, Prospect has a total area of 4.1 square miles (10.6 km2), all land.

The racial makeup of the borough was 99.35% White, 0.08% Native American, 0.08% Pacific Islander, and 0.49% from two or more races.