Washington Township is one of four townships in Brown County, Indiana. As of the 2020 census, its population was 5,164 and it contained 2,753 housing units. The township includes the northern portion of Brown County State Park.
Washington Township was established in 1836.
The Brown County Bridge No. 36 and Theodore Clement Steele House and Studio are listed on the National Register of Historic Places.
According to the 2010 census, the township has a total area of , of which (or 97.47%) is land and (or 2.53%) is water. Axsom Branch Pond and Terrill Ridge Pond are in this township.
(This list is based on USGS data and may include former settlements.)
The township contains eight cemeteries: Clark, Crouch, David, Dobbs, Hickory Hill, Marlett, Pittman, South View, and Terrill.