Collinsville Township is located in Madison County, Illinois, in the United States. As of the 2010 census, its population was 36,265 and it contained 16,407 housing units.
Collinsville Township takes its name from the city of Collinsville.
According to the 2010 census, the township has a total area of , of which (or 97.57%) is land and (or 2.43%) is water.