State Route 166 (SR 166) is a short route in Coffee County in the southeastern part of the state.

The western terminus of the route is at its junction with SR 141 at Danleys Crossroads, an unincorporated community in the western part of the county.

The route traverses along a two-lane road in western Coffee County, passing through no towns or unincorporated communities until it reaches Elba.

The original route began at an intersection approximately 10 miles (16 km) northwest of Opp.

In 1989, SR 166 and US 84 exchanged routings between SR 141 and Elba as part of improvements, including widening to four lanes, of US 84 across south Alabama.