Marion Township is one of nine townships in Decatur County, Indiana, United States. As of the 2020 census, its population was 1,711 (up from 1,638 at 2010) and it contained 674 housing units.
Marion Township was organized in 1831.
According to the 2010 census, the township has a total area of , of which (or 99.89%) is land and (or 0.11%) is water.
(This list is based on USGS data and may include former settlements.)
The township contains four cemeteries: Antioch, Burks Chapel, Mount Pleasant, and Immaculate Conception Catholic Cemetery.