Marienville is an unincorporated community and census-designated place (CDP) in Jenks Township, Forest County, Pennsylvania, United States. Its altitude is 1735 ft, and it is located at 41.47°N, -79.12472°W (41.4702014, -79.1247623). Other names for the community have included "Marion" and "Marionville". Marienville is a major point on a well-known ATV trail. According to the 2010 census the population of Marienville was 3,137.