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.

The Southeast Missouri Lead District, commonly called the Lead Belt, is a lead mining district in the southeastern part of Missouri. Counties in the Lead Belt include Saint Francois, Crawford, Dent, Iron, Madison, Reynolds, and Washington. This mining district is the most important and critical lead producer in the United States.