Reynolds County is a county located in the Ozark Foothills Region in the Lead Belt of Missouri. As of the 2020 census, the population was 6,096. Its county seat is Centerville. The county was officially organized on February 25, 1845, and was named in honor of former Governor of Missouri Thomas Reynolds.

Johnson's Shut-Ins State Park is a public recreation area covering 8,781 acres (3,554 ha) on the East Fork Black River in Reynolds County, Missouri. The state park is jointly administered with adjoining Taum Sauk Mountain State Park, and together the two parks cover more than sixteen thousand acres in the St. Francois Mountains region of the Missouri Ozarks.