Washington Township is one of the twelve townships in Adams County, Indiana. As of the 2020 census, its population was 8,654, down from 10,151 at the 2010 census.
According to the 2010 census, the township has a total area of , of which (or 99.92%) is land and (or 0.11%) is water.
The township contains the following cemeteries: Antioch (also known as Beery or River Brethren), County Home (or Farm or Infirmary- no longer exists), Greenwood (also known as Decatur or Maplewood), First City (no longer exists), Little Family, and Roe (no longer exists).