Monticello is a village in Lewis County, Missouri, United States, along the North Fabius River. The population was 126 at the 2000 census. It is the county seat of Lewis County.
Monticello is part of the Quincy, IL–MO Micropolitan Statistical Area.
Monticello is located at 40°7′4″N 91°42′51″W / 40.11778°N 91.71417°W / 40.11778; -91.71417 (40.117841, -91.714152). According to the United States Census Bureau, the village has a total area of 0.3 square miles (0.7 km²), all of it land.