Bollinger County is a county located in the southeastern part of the U.S. state of Missouri. As of the 2020 census, the county's population was 10,567. The county seat, largest and only city, is Marble Hill. The largely rural county is supported by agriculture and construction. The county was officially organized in March 1851 from portions of Wayne, Cape Girardeau and Stoddard Counties, and named in honor of George Frederick Bollinger, an early settler.