Boyne City is a city in Charlevoix County in the U.S. state of Michigan. The population was 3,816 at the 2020 census, making it the largest city in Charlevoix County. Boyne City is located at the eastern end of Lake Charlevoix, Michigan's third largest inland lake. The city is also the site of the mouth of the Boyne River, named for the River Boyne in Leinster, Ireland.