Wilmington Township is one of fifteen townships in DeKalb County, Indiana. As of the 2020 census, its population was 3,995 (down from 4,128 at the 2010 census) and it contained 1,600 housing units.
Wilmington Township was organized in 1837.
According to the 2010 census, the township has a total area of , of which (or 99.97%) is land and (or 0.03%) is water.
The township contains two cemeteries: Kraft and Krontz.