Sibley is a city in Osceola County, Iowa, United States. The population was 2,860 at the time of the 2020 census. It is the county seat of Osceola County. Hawkeye Point, the highest point in the State of Iowa, is also nearby.

Osceola County is a county located in the U.S. state of Iowa. As of the 2020 census the population was 6,192, making it the state's fifth-least populous county. It is named for Seminole war chief Osceola. The county seat is Sibley, named for H. H. Sibley of Minnesota.