Gridley Township is located in McLean County, Illinois. As of the 2010 census, its population was 1,913 and it contained 790 housing units.
Gridley Township was named for Asahel Gridley, an Illinois state senator.
According to the 2010 census, the township has a total area of , of which (or 99.96%) is land and (or 0.02%) is water.