Marienville is an unincorporated community and census-designated place (CDP) in Jenks Township, Forest County, Pennsylvania, United States.

The community is in southeastern Forest County near the center of Jenks Township.

Pennsylvania Route 66 is the main street, leading northeast 24 miles (39 km) to U.S. Route 6 at Kane and southwest 27 miles (43 km) to Interstate 80 near Clarion.

Pennsylvania Route 899 leads south from Marienville 10 miles (16 km) to Clarington.

According to the U.S. Census Bureau, the Marienville CDP has a total area of 6.1 square miles (15.7 km2), all land.