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.
Jonathan Tharp, who settled Pekin, and his family laid out a town to be called Cincinnati. This planned town was between the Illinois River and Broadway, McLean, and Main streets. Although this site was absorbed by Pekin as its population grew, Cincinnati Township is named after this town site.
According to the 2010 census, the township has a total area of , of which (or 98.85%) is land and (or 1.18%) is water.
As of 2016, approximately 9220 people live in the area.