State Route 850 (SR 850, OH 850) is a north–south state highway in southeastern Ohio, a U.S. state. Its southern terminus is at State Route 588 in the hamlet of Rodney, which is west of Gallipolis. State Route 850's northern terminus is at State Route 554 in Bidwell. The route has an interchange with U.S. Route 35, but otherwise intersects with no other numbered routes.

All of State Route 850 runs within Gallia County. The route is not inclusive within the National Highway System.

State Route 850 was created in 1995 along its current routing between State Route 588 and State Route 554, designated in approximately the same timeframe that the U.S. Route 35 freeway was completed east of Rio Grande. No significant changes have taken place to the highway's routing since its debut.

The entire route is in Gallia County.