The highway connects mostly rural areas of Washington and Mercer counties with Harrodsburg.

It travels through Seaville and intersects the western terminus of KY 1160 (Talmage–Mayo Road) on the Mercer County line.

It curves to the southeast and crosses over some railroad tracks of Norfolk Southern Railway.

KY 390 turns left onto Industry Road, to the east-northeast, and leaves the city limits of Harrodsburg.

It then curves to the east-southeast and meets its eastern terminus, an intersection with U.S. Route 127 (US 127; North College Street / Louisville Road).