Washington Township is one of four townships in Blackford County, Indiana. As of the 2020 census, its population was 803 (down from 873 at 2010) and it contained 364 housing units. County Commissioners named the township after George Washington in 1833, and it was part of Jay County. In 1838, Washington Township became part of the newly organized Blackford County.
According to the 2010 census, the township has a total area of , of which (or 99.97%) is land and (or 0.03%) is water.
The township contains at least nine cemeteries: Balsley, Center, Hadden, Herbaugh, Leffler, Mills, Roll, Shields, and Schmidt.