Clay County is a county in the U.S. state of Nebraska. As of the 2020 United States Census, the population was 6,104. Its county seat is Clay Center. The county was formed in 1855, and was organized in 1871. It was named for Henry Clay, a member of the United States Senate from Kentucky, who went on to become United States Secretary of State.

Clay Center is a city in and the county seat of Clay County, Nebraska, United States. It is part of the Hastings, Nebraska Micropolitan Statistical Area. The population was 760 at the 2010 census.