Clarke County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 9,748. The county seat is Osceola. The county was formed in January 1846, one of twelve counties established by legislative action in a comprehensive act. It was named for James Clarke, a Governor of the Iowa Territory.

Osceola is a city in Clarke County, Iowa, United States. The population was 5,160 at the time of the 2020 census. It is the county seat of Clarke County.