Harrison Township is one of four townships in Blackford County, Indiana. As of the 2020 census, its population was 2,353 (down from 2,640 at 2010) and it contained 1,155 housing units. The township was named after William Henry Harrison, hero of the Battle of Tippecanoe, former governor of the Indiana Territory, and ninth President of the United States.
According to the 2010 census, the township has a total area of , of which (or 99.76%) is land and (or 0.24%) is water. Lake Blue Water and the Godfrey Reserve are in this township. The Salamonie River runs through the township's northeast corner.
The township contains at least eight cemeteries: Brookside, Independent Order of Odd Fellows, North Twibell, Penrod, Pleasantdale, South Twibell, St Margaret's Roman Catholic, and Woodlawn.