State Route 85 (SR 85, OH 85) is an east–west state highway in the northeastern Ohio. The western terminus of State Route 85 is at a traffic circle in Andover where it intersects the duplex of U.S. Route 6 and State Route 7. Its eastern terminus is just over 2.5 miles (4.0 km) east of Andover at the Pennsylvania State Line in the middle of the Pymatuning Causeway, where Pennsylvania Route 285 continues east.

The shortest of three state routes that lie completely within Ashtabula County, the current State Route 85 is a fraction of the route it was when first designated in the mid-1920s, when it ran from Euclid to Andover and onto the Pymatuning Causeway. When U.S. Route 6 was designated in Ohio in the early 1930s, State Route 85 was at first co-signed with the U.S. highway from Euclid to Andover, but by the late 1930s, the State Route 85 shields were removed from this stretch of roadway, leaving just the stretch of highway that exists today.

The entirety of State Route 85 is situated in the eastern portion of Ashtabula County. No part of State Route 85 is included within the National Highway System, a system of routes deemed most important for the economy, defense and mobility of the country.

State Route 85 begins at a traffic circle in downtown Andover where it meets U.S. Route 6 and State Route 7. The two-lane state highway, which trends generally due east for its entire length, departs from the traffic circle and passes through a primarily commercial stretch of roadway to the point where it crosses the village limits of Andover, and enters into Andover Township. The tree-lined highway passes a blend of businesses and residences en route to the signalized intersection where it meets Pymatuning Lake Road, a road that follows the western edge of the Pymatuning Reservoir, and connects State Route 85 with the facilities of Pymatuning State Park. East of the traffic light, State Route 85 traverses the Pymatuning Causeway, which crosses the middle of the Pymatuning Reservoir. Approximately halfway across the causeway, the roadway hits the Pennsylvania State Line. At that point, State Route 85 comes to an end, and Pennsylvania Route 285 picks up the rest of the route across the causeway.

State Route 85 made its debut in 1924, consisting of what is now the stretch of U.S. Route 6 between Euclid and Andover, as well as the entirety of the current State Route 85 from Andover to the Pennsylvania State Line. When U.S. Route 6 made its debut in Ohio in 1932, it was routed via the stretch of State Route 85 between Euclid and Andover. For the six years following, U.S. Route 6 and State Route 85 were run concurrently along that stretch of roadway. In 1938, State Route 85 was truncated to its current routing between Andover and the connection to Pennsylvania Route 285 on the Pymatuning Causeway, leaving U.S. Route 6 to be the lone route running between Euclid and Andover.

The entire route is in Ashtabula County.