After US 25 breaks away and goes north toward the Blue Grass Army Depot, KY 21 continues to the east and intersects US 421 in Bighill before ending at the Jackson County line.

The road passes through farmland with some trees and homes, curving south before heading back to the southeast.

The route continues south and then southeast through more rural areas and comes to an intersection with the eastern terminus of KY 954.

[1][2] At this point, US 25 joins KY 21 for a concurrency and the two routes pass through residential areas as a two-lane undivided road.

The route becomes Big Hill Road and curves east to leave Berea, heading through farmland with some homes and crossing KY 1617.