Wilder is a home rule-class city in Campbell County, Kentucky, United States. The population was 3,176 at the 2020 census. It is part of th…Wilder is a home rule-class city in Campbell County, Kentucky, United States. The population was 3,176 at the 2020 census. It is part of the Cincinnati-Northern Kentucky metropolitan area. According to the United States Census Bureau, the city has a total area of 3.8 square miles, of which 3.7 square miles is land and 0.1 square miles is water.