[3] Nokomis is in eastern Montgomery County, along Illinois Route 16 (State Street), which leads southwest 16 miles (26 km) to Hillsboro and northeast 13 miles (21 km) to Pana.

According to the U.S. Census Bureau, Nokomis has a total area of 1.3 square miles (3.37 km2), all land.

[2] The city sits at the headwaters of the East Fork of Shoal Creek, a south-flowing tributary of the Kaskaskia River.

The racial makeup of the city was 99.46% White, 0.25% Native American, 0.04% Asian, and 0.25% from two or more races.

[citation needed] Ramsey Lake State Recreation Area is 19 miles (31 km) southeast of Nokomis.