Washington Township is one of twelve townships in Boone County, Indiana. As of the 2010 census, its population was 1,398 and it contained 547 housing units.
According to the 2010 census, the township has a total area of , of which (or 99.61%) is land and (or 0.39%) is water.
The township contains three cemeteries: Bethel, Bethel Hill and Brush Creek.