South Bethlehem is a borough in Armstrong County, Pennsylvania, United States.

[5] It is bordered to the northeast by the borough of New Bethlehem, which is across Redbank Creek in Clarion County.

Pennsylvania Routes 28 and 66 pass through South Bethlehem, leading southwest 19 miles (31 km) to Kittanning.

According to the U.S. Census Bureau, South Bethlehem has a total area of 0.15 square miles (0.4 km2), all land.

South Bethlehem appears on the 1876 Atlas of Armstrong County Pennsylvania.