Moniteau County is a county located in the U.S. state of Missouri. As of the 2020 United States census, the population was 15,473. Its county seat is California. The county was organized February 14, 1845 and named for the Moniteau Creek. 'Moniteau' is a French spelling of Manitou, Algonquian for the Great Spirit. Moniteau County is part of the Jefferson City, MO Metropolitan Statistical Area.