Cincinnati Township is located in Tazewell County, Illinois. As of the 2010 census, its population was 9,506 and it contained 3,436 housing units. The township is based in the Village of South Pekin, Illinois.
According to the 2010 census, the township has a total area of 30.39 square miles (78.7 km2), of which 30.04 square miles (77.8 km2) (or 98.85%) is land and 0.36 square miles (0.93 km2) (or 1.18%) is water.
Coordinates: 40°31′04″N 89°39′46″W / 40.51778°N 89.66278°W / 40.51778; -89.66278