Sedgwick County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 2,404. The county seat is Julesburg. The county was named for Fort Sedgwick, a military post along the Platte Trail, which was named for General John Sedgwick. It is located near the state border with Nebraska.

Julesburg is the statutory town that is the county seat and the most populous municipality of Sedgwick County, Colorado, United States. The population was 1,307 at the 2020 United States Census.