Mount Carbon is a census-designated place (CDP) in Fayette County, West Virginia, United States. Mount Carbon is located along West Virginia Route 61, southeast of Montgomery, on the south bank of the Kanawha River at the mouth of Armstrong Creek. Mount Carbon has a post office with ZIP code 25139. As of the 2020 census, its population was 341 (down from 428 at the 2010 census).
Mount Carbon was named for nearby coal deposits, a carbon-based fuel.