Mendon is a village in Adams County, Illinois, United States. The population was 883 at the 2000 census. It is part of the Quincy, IL–MO Micropolitan Statistical Area.
Mendon is located at 40°5′18″N 91°17′4″W / 40.08833°N 91.28444°W / 40.08833; -91.28444 (40.088241, -91.284458).
According to the United States Census Bureau, the village has a total area of 0.7 square miles (1.9 km²), all of it land.