Cynthiana is a home rule-class city in Harrison County, Kentucky, in the United States. The population was 6,402 at the 2010 census. It is the seat of its county.

Harrison County is a county located in the U.S. state of Kentucky. As of the 2020 census, the population was 18,692. Its county seat is Cynthiana. The county was founded in 1793 and named for Colonel Benjamin Harrison, an advocate for Kentucky statehood, framer of the Kentucky Constitution, and Kentucky legislator.