Washington Township is one of fourteen townships in Cass County, Indiana, and one of the forty-six townships sharing the name in the state. As of the 2020 census, its population was 1,557 (down from 1,608 at 2010) and contained 708 housing units.
Washington Township was organized in 1842. It was named for George Washington, first President of the United States.
Washington Township covers an area of ; (0.51 percent) of this is water.
The township contains four cemeteries: Bruner, Ramer, Taber and West.