Wayne County is a county in the U.S. state of Michigan. As of the 2000 census, its population was 2,061,162 with the July 1, 2008 estimate placing the population at 1,949,929 making it the 13th most-populous county in the United States. The county seat is Detroit, the largest city in Michigan. The County executive is Bob Ficano.

According to the U.S. Census Bureau, the county has a total area of 672 square miles (1,741 km²)—614 square miles (1,591 km²) of it is land and 58 square miles (150 km²) of it (8.64%) is water (including parts of the Detroit River and Lake St. Clair).

Wayne County borders on Oakland County and Macomb County to the north, Washtenaw County to the west, and Monroe County to the south.