Fillmore is a village in Montgomery County, Illinois, United States.

[3] Fillmore is in southeastern Montgomery County, 14 miles (23 km) east-southeast of Hillsboro, the county seat, and 18 miles (29 km) northwest of Vandalia.

According to the U.S. Census Bureau, Fillmore has a total area of 1.02 square miles (2.64 km2), all land.

[2] Lanes Branch flows through the west side of the village, running southwest to the Dry Fork of Hurricane Creek, part of the Kaskaskia River watershed.

27.1% of all households were made up of individuals, and 16.0% had someone living alone who was 65 years of age or older.