Eaton County is a county in the U.S. state of Michigan. As of the 2020 United States Census, the population was 109,175. The county seat is Charlotte. The county was organized in 1837 and was named for John Eaton, who was Secretary of War under U.S. President Andrew Jackson, making it one of Michigan's Cabinet counties. Eaton County is included in the Lansing-East Lansing, Metropolitan Statistical area in Central Michigan.

Charlotte is a city and county seat of Eaton County, Michigan. As of the 2010 census, the city population was 9,074.