The route originates at a junction with U.S. Route 127 in the southern Russell County community of Freedom. The route continues into Adair County through Columbia. In the 2010s, KY 55 was rerouted onto the Columbia Bypass, while the original KY 55 alignment, which went through town and provided Cumberland Parkway access, was re-designated as KY 55 Business. The route continues northward, bypassing the Green River Lake State Park, and on to U.S. Route 68 in Campbellsville, Taylor County, where KY 55 joins US 68 east, and also runs concurrently with KY 70 for the remaining of that route's concurrency with US 68. US 68 and KY 55 continues north into Marion County.
Marion County through Spencer County
At Lebanon, KY 55 splits from US 68 and continues to Springfield, Washington County, running into downtown Springfield and crossing US 150. It continues north-northwestwardly into eastern Nelson County, providing access to the Bluegrass Parkway and US 62 at Bloomfield. KY 55 goes further north to Spencer County, and goes through Taylorsville.
From Spencer County, KY 55 runs northeast into Shelby County. The route runs through open fields with occasional houses lining the road. into Shelby County, KY 55 intersects with KY 148 and enters the community of Finchville. In Finchville the route is lined with houses and a few businesses, and the speed limited is reduced to 35 MPH. After meeting the eastern terminus of KY 1848, KY 55 leaves Finchville and heads north toward Shelbyville. In Shelbyville, KY 55 crosses Interstate 64 at Exit 32. Currently, KY 55 widens to 4 lanes with a center turning lane a few tenths of a mile north of the Interstate. However, construction is currently going on to widen the road to 4 lanes starting just south of the interstate as part of the I-64 widening project. North of I-64, many businesses line KY 55 as well as 3 industrial parks. north of the interstate, KY 55 intersects with US 60 / KY 55 Business and becomes the Shelbyville Bypass. The Shelbyville Bypass opened up in November 2010, and is a 4.5 mile 4-lane divided highway. The Shelbyville Bypass runs north then curves east, crossing KY 53 near Shelby County West Middle School. The route continues east, crossing over Clear Creek and ends north of Shelbyville at an intersection with KY 55 Business. North of the Shelbyville Bypass, KY 55 becomes Eminence Pike and narrows to two-lanes as it heads north passing open fields and houses before entering into Henry County roughly further north. In Henry County, KY 55 enters the city of Eminence and forms a concurrency with KY 22 for. It continues north out of town and forms a concurrency with US 421 north of KY 22. After passing by Henry County High School and traveling through New Castle, US 421 and KY 55 split in Campbellsburg. Roughly north of US 421, KY 55 passes over Interstate 71 and enters into Trimble County, where it travels for a short distance. The route intersects KY 316 at its eastern terminus and continues northward into Carroll County just over from the Trimble County-Henry County line. In Carroll County, KY 55 curves toward the northeast, passing KY 549 and KY 389 in rural sections of the county. After the intersection with KY 389, the route turns toward the northwest and travels along the Kentucky River on the east, with mainly woods on the west. As it nears Presntonville, KY 55 turns toward the west, then northeast, then north at New Castle Pike. In Prestonville, it passes by a few homes before it ends at an intersection with US 42/KY 36, just west of the Kentucky River and south of the Ohio River. The entire route remains two-lanes throughout Henry, Trimble, and Carroll counties.
Major intersections
Special routes
Columbia business route
Kentucky Route 55 Business is a business route of KY 55 in Columbia. The highway runs between junctions with KY 6177/KY 55 south of Columbia and KY 55 north of Columbia. The route runs north from its southern terminus and passes over the Louie B. Nunn Cumberland Parkway as it enters Columbia. from KY 55 south of Columbia, the route forms a concurrency with KY 80 and turns northwest as it passes through the heart of town. At an intersection with KY 80 and KY 439, it turns toward the north. KY 55 Business intersects KY 206 as it continues its northward path out of Columbia. A little over north of KY 206, KY 55 Business ends at an intersection with KY 55.
Lebanon spur
Kentucky Route 55 Spur in Lebanon is long and connects KY 55 to US 68 in the heart of downtown Lebanon.
Shelbyville business route
Kentucky Route 55 Business is a business route of KY 55 in Shelbyville. The highway runs between junctions with US 60/KY 55 west of Shelbyville and KY 55 north of Shelbyville. The route was formed in 2010 with the completion of the Shelbyville Bypass, which re-routed KY 55 around Shelbyville. The old route that passed through Shelbyville became KY 55 Business. For the first 3.074 miles, the route forms a concurrency with US 60 and is a four-lane highway. From its origin, it passes through a commercial area of Shelbyville with many businesses and shopping centers lining the roadway. Roughly from its origin, KY 55 Business splits into two one-way routes, Main Street going west to east, and Washington Street going east to west. Here it also forms a concurrency with KY 53. The route passes through downtown Shelbyville and the one-way routes join together just east of downtown. The route then departs with US 60 and KY 53 and turns north and becomes a two-lane highway, passing by multiple businesses and subdivisions. After intersecting KY 43 and KY 2268, it continues north for roughly before ending at KY 55 north of Shelbyville.
