El Dorado is a city and county seat of Butler County, Kansas, United States. It is situated along the Walnut River in the central part of Butler County and located in south-central Kansas. As of the 2020 census, the population of the city was 12,870. It is home to Butler Community College.

Butler County is a county in the U.S. state of Kansas and is the largest county in the state by total area. Its county seat is El Dorado and its most populous city is Andover. As of the 2020 census, the county population was 67,380. The county was named for Andrew Butler, a U.S. Senator from South Carolina who coauthored the Kansas–Nebraska Act.