Illinois Route 185 is an east–west state road in the south-central portion of the U.S. state of Illinois. Its western terminus is in Taylor Springs at Illinois Route 127, and the eastern terminus is at Farina at Illinois Route 37. This is a distance of 49.88 miles (80.27 km).

Illinois 185 runs geographically northwest-southeast through south-central Illinois. It overlaps both U.S. Route 40 and U.S. Route 51 through the city of Vandalia.

SBI Route 185 originally ran from Bluff City to Farina. In 1949, it was extended northwest to Taylor Springs.