High Quality Content by WIKIPEDIA articles! High Quality Content by WIKIPEDIA articles! Jessamine County is a county located in the U.S. state of Kentucky. It is within the Inner Blue Grass region, which was the center of farming and blooded stock raising, including thoroughbred horses. It was formed in 1799. As of 2000, the population was 39,041. The 2008 population estimate was 46,716. Its county seat is Nicholasville. Jessamine County is part of the Lexington-Fayette, KY Metropolitan Statistical Area.