Fond du Lac County is a county located in the U.S. state of Wisconsin. As of the 2010 census, the population was 101,633. Its county seat is Fond du Lac. The county was created in the Wisconsin Territory in 1836 and later organized in 1844. Fond du Lac is French for "bottom of the lake", so given because of the county's location at the southern shore of Lake Winnebago.