Wilmington is a city in and the county seat of Clinton County, Ohio, United States. The population was 12,664 at the 2020 census. It is the principal city of the Wilmington micropolitan area, which includes all of Clinton County and is part of the greater Cincinnati–Wilmington–Maysville combined statistical area. Home to Wilmington College, founded in 1870 by the Society of Friends, the city and the surrounding area include more than one dozen Quaker meeting houses.