Monticello is a rural village in Lewis County, Missouri, United States, and serves as the county seat of Lewis County. It is located along the North Fabius River in the northeastern part of the state.
The population was 104 at the 2020 census. According to that census, Monticello is the county seat with the smallest population in the State of Missouri. The town is named in honor of President Thomas Jefferson's estate in Virginia.
Monticello is part of the Quincy, IL–MO Micropolitan Statistical Area.