Petersburg is a city in Washington Township, Pike County, Indiana, United States. The population was 2,383 at the 2010 census. The city is the county seat of Pike County.
Petersburg is part of the Jasper Micropolitan Statistical Area.
Petersburg is located at 38°29′30″N 87°16′49″W / 38.49167°N 87.28028°W / 38.49167; -87.28028 (38.491653, -87.280372).