The county was named in 1803 for Christopher Greenup, governor of Kentucky from 1804 to 1808. Born in Virginia in 1750, he was an officer in the American Revolution. He began practicing law in Kentucky in 1783 and served as clerk of the Virginia court for the district of Kentucky from 1785 to 1792. He was a member of the conventions for Kentucky statehood in 1784, 1785, and 1788, was elected as one of the first two Kentucky members of the U.S. Congress from 1793 to 1797, served as a presidential elector in 1808, and died in 1818, being buried in Frankfort Cemetery.