Tennessee State Route 125 is a State Route in southwestern Tennessee in Hardeman County. It begins in the center of Bolivar, Tennessee and travels southward for a total of approximately twenty miles to its end at the Tennessee/Mississippi state line, where it continues as Mississippi Highway 15.

Tennessee State Route 125 begins in the center of Bolivar, Tennessee as the end of State Route 18, crossing Market Street (State Route 15/U. S. Route 64) and heading southeast. After leaving Bolivar, the road runs through rural areas for approximately 12 miles until entering Middleton, and turning nearly due south. Then, it crosses the Norfolk Southern Railway and State Route 57, before leaving Middleton. From there, State Route 125 continues on (now running parallel to the defunct Kansas City Southern Railway) for approximately three miles until terminating at the Tennessee/Mississippi state line, where it continues as Mississippi Highway 15.