State Route 690 (SR 690, OH 690) is a north–south state highway in southeastern Ohio, a U.S. state. The southern terminus of State Route 690 is at the duplex of U.S. Route 50 and State Route 32 about 6.50 miles (10.46 km) east of Athens. Its northern terminus is at State Route 550 approximately 2 miles (3.2 km) west of Amesville.

This two-lane state highway was established in the late 1930s. Running entirely within Athens County, State Route 690 passes through Wayne National Forest and serves as a quicker route connecting State Route 550 to the Athens Bypass.

State Route 690 runs exclusively within Athens County. This state highway is not included as a part of the National Highway System, a network of highways deemed to be most important for the economy, mobility and defense of the nation.

State Route 690 made its debut in 1937 along the routing that it occupies to this day. Other than the fact that the highway intersecting State Route 690 at its northern terminus was originally designated as U.S. Route 50 Alternate before later becoming State Route 550, the highway has not experienced any major changes to its routing since it first appeared.

The entire route is in Athens County.