Charlevoix County is a county in the U.S. state of Michigan. The county seat is Charlevoix, and the largest city is Boyne City. Located in the Northern Lower Peninsula, Charlevoix County is bisected by Lake Charlevoix, Michigan's third largest inland lake. As of the 2020 census, the county's population was 26,054. Beaver Island, the largest island in Lake Michigan, is located within Charlevoix County.