State Route 501 (SR 501) is a north–south state highway in western Ohio. The southern terminus of State Route 501 is at a parclo AB-2 interchange with U.S. Route 33 just south of Wapakoneta, which is also the western terminus for State Route 67 and the southern terminus for State Route 198. The route runs concurrently with both of the other two routes into Wapakoneta, and with State Route 198 only north of the village. State Route 501’s northern terminus is at State Route 117 approximately 6 miles (9.7 km) west of Lima.

State Route 501 runs through portions of Auglaize and Allen Counties. The highway is not incorporated within the National Highway System, a system of highways established to be the most important for the nation's economy, mobility and defense.

When first established in 1937, State Route 501 ran from downtown Wapakoneta to its current northern terminus at State Route 117. When a new southern bypass of Wapakoneta was completed in 1961 and U.S. Route 33 was re-routed along it, State Route 501, along with State Route 67 and State Route 198, were extended south from downtown along Willipie Street to a new common terminus at the re-routed U.S. Route 33.