Sibley is a city in Osceola County, Iowa, United States. The population was 2,798 at the 2010 census. It is the county seat of Osceola County. It is named after Henry Hastings Sibley, a prominent General during the Dakota War of 1862, who eventually became the first territorial governor of Minnesota. William L. Harding, governor of Iowa from 1917 to 1921, was born in Sibley in 1877. Hawkeye Point, the highest point in the State of Iowa, is also nearby.