Illinois Township is one of nineteen current townships in Pope County, Arkansas, USA. As of the 2010 census, its total population was 29,813, with 91.8 percent (approx. 27,370 people) contained in urban Russellville.
According to the United States Census Bureau, Illinois Township covers an area of , with of it land and of water.
The township contains Lake Dardanelle and Lake Dardanelle State Park.