Union Township is one of fourteen townships in Miami County, Indiana, United States. As of the 2020 census, its population was 764 (down from 857 at 2010) and it contained 349 housing units.
Union Township was first settled in the spring of 1835. Union Township was organized in 1837.
According to the 2010 census, the township has a total area of , of which (or 99.59%) is land and (or 0.37%) is water.
The township contains these five cemeteries: Ebenezer, Independent Order of Odd Fellows, Mount Zion, Leedy and Weasaw.