Scott County is a county located in the U.S. state of Illinois. According to the 2020 census, it had a population of 4,949, making it the fourth-least populous county in Illinois. Its county seat is Winchester.

Winchester is a city in and the county seat of Scott County, Illinois, United States. The population was 1,593 at the 2010 census. Winchester is part of the Jacksonville Micropolitan Statistical Area.