NY 157 begins at an intersection with NY 156 (Berne–Altamont Road) in the town of Berne. The route proceeds southeast along Thompson's Lake Road, a two-lane, rural, asphalt road through Berne and climbing down a hill before reaching an intersection with NY 157A (Warners Lake Road). After NY 157A, the route runs east through Berne, reaching an intersection with Old Stage Road. At this junction, the route turns southward, crossing past more residences and farms and an intersection with the western terminus of County Route 256 (CR 256, named Ketcham Road). At the junction with Singer Road, NY 157 turns southeast once again, crossing past similar surroundings.