Union Township is one of ten townships in Marshall County, Indiana, United States. As of the 2020 census, its population was 2,771 (down from 3,088 at 2010) and it contained 1,949 housing units.
Union Township was organized in 1840. It was likely named after Union County, Indiana, the former home of some of the early settlers.
The East Shore Historic District and Norris Farm-Maxinkuckee Orchard are listed on the National Register of Historic Places. Woodbank was delisted in 2014.
According to the 2010 census, the township has a total area of , of which (or 92.83%) is land and (or 7.19%) is water.
(This list is based on USGS data and may include former settlements.)
The township contains these five cemeteries: Burr Oak, Cromley, Masonic, Washington and Zion.
The township is served by the Culver-Union Township Public Library.