Union Township is one of thirteen townships in St. Joseph County, in the U.S. state of Indiana. As of the 2020 census, its population was 3,478.
According to the United States Census Bureau, Union Township covers an area of ; of this, (99.52 percent) is land and (0.48 percent) is water.
(This list is based on USGS data and may include former settlements.)
The township contains Lakeville Cemetery.