Washington Township is one of eleven townships in Ripley County, Indiana. As of the 2020 census, its population was 2,257 (down from 2,440 at 2010) and it contained 895 housing units.
According to the 2010 census, the township has a total area of , of which (or 99.93%) is land and (or 0.07%) is water.
Washington Township residents may obtain a free library card from the Osgood Public Library Central Library in Osgood, or its branch in Milan.