Jessamine County is a county located in the U.S. state of Kentucky. As of the 2020 census, the population was 52,991. Its county seat is Nicholasville. The county was founded in December 1798. Jessamine County is part of the Lexington-Fayette, KY Metropolitan Statistical Area. It is within the Inner Blue Grass region, long a center of farming and blooded stock raising, including thoroughbred horses. The legislature established a commercial wine industry here in the late 18th century.

Nicholasville is a home rule city in and the county seat of Jessamine County, Kentucky. The population was 31,490 during the 2020 U.S. census, making Nicholasville the 10th-largest settlement in the state.