Fond du Lac County is a county in the U.S. state of Wisconsin. As of the 2020 census, the population was 104,154. 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", given so because of the county's location at the southern shore of Lake Winnebago. Fond du Lac County comprises the Fond du Lac, Wisconsin Metropolitan Statistical Area.