Kentucky Route 55 (KY 55) is a 147.227 mile (236.939 km) long state highway in the U.S. state of Kentucky. The route originates at a junction with U.S. Route 127 in Freedom, Russell County. The route continues through Columbia in Adair County to U.S. Route 68 in Campbellsville, Taylor County, where KY 55 joins US 68 east to Lebanon in Marion County.

In Lebanon, KY 55 separates from US 68 and proceeds northward through Springfield in Washington County, Bloomfield in Nelson County, Taylorsville and Elk Creek in Spencer County, Shelbyville in Shelby County, and Eminence in Henry County. Roughly three miles south of New Castle, KY 55 intersects U.S. Route 421. The two routes run concurrent for eight miles (13 km) before splitting near Campbellsburg. KY 55 continues north to Prestonville, where it ends at an intersection with U.S. Route 42 and Kentucky Route 36 on the bank of the Ohio River.