Oscoda County is a county in the U.S. state of Michigan. As of the 2020 census, the population was 8,219, making it the least populous county in the Lower Peninsula, and the sixth-least populous county in the entire state. The county seat is Mio, an unincorporated community near the center of the county.

Mio is an unincorporated community and census-designated place (CDP) in Oscoda County in the U.S. state of Michigan. It is the county seat of Oscoda County. The population of the CDP was 1,690 at the 2020 census.