St. Petersburg is a borough in Clarion County, Pennsylvania, United States.

[4] Pennsylvania Route 58 passes through the borough, leading 2 miles (3 km) southwest to Foxburg on the Allegheny River and east 7 miles (11 km) to Callensburg on the Clarion River.

Pennsylvania Route 478 leads northwest 2 miles (3 km) to Interstate 80 east of Emlenton.

According to the United States Census Bureau, St. Petersburg has a total area of 0.32 square miles (0.83 km2), all land.

St. Petersburg is the birthplace of silent film actress and thelemite Jane Wolfe (1875–1958).