Chautauqua County is a county located in Southeast Kansas, United States. Its county seat and most populous city is Sedan. As of the 2020 census, the county population was 3,379. The county is named for Chautauqua County, New York, the birthplace of Edward Jaquins, a Kansas politician who was instrumental in getting the county established.

Sedan is the county seat of and the largest city in Chautauqua County, Kansas, United States. As of the 2020 census, the population of the city was 1,000.