PA 157 begins at an intersection with US 62 in Cranberry Township, Venango County, heading south-southeast on a two-lane undivided road. The route heads through wooded areas with occasional homes, curving east into more woodland with some farm fields and residences. The road passes through Stanleys Corners and Sadlers Corners before crossing into Pinegrove Township. Here, PA 157 becomes Fryburg Road and runs through more rural areas, heading through Coal Hill and Hampton Station. The road continues through more forests with some farmland and homes, turning southeast and coming to Venus. At this point, PA 157 heads into Washington Township in Clarion County and continues southeast through more agricultural areas with some woods and residences. The route turns east and comes to its eastern terminus at an intersection with PA 208, where Fryburg Road continues east as part of PA 208.