Shiawassee County is a county located in the U.S. state of Michigan. As of the 2020 United States Census, the population was 68,094. The county seat is Corunna, and the largest city in the county is Owosso. In 2010, the center of population of Michigan was located in Shiawassee County, in Bennington Township. Shiawassee County is included in the Lansing-East Lansing, MI Metropolitan Statistical Area.