| Official Name: | Union Township, Black Hawk County |
| Settlement Type: | Township |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Type2: | County |
| Subdivision Name2: | Black Hawk |
| Area Total Km2: | 47.33 |
| Area Land Km2: | 46.7 |
| Area Water Km2: | 0.63 |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 18.27 |
| Area Land Sq Mi: | 18.03 |
| Area Water Sq Mi: | 0.24 |
| Population As Of: | 2000 |
| Population Total: | 941 |
| Population Density Km2: | 20.1 |
| Population Density Sq Mi: | 52.2 |
| Elevation Footnotes: | [1] |
| Elevation M: | 288 |
| Elevation Ft: | 945 |
| Coordinates: | 42.6067°N -92.5256°W |
| Blank Name: | FIPS code |
| Blank Info: | 19-94173[2] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 0468809 |
Union Township is one of seventeen rural townships in Black Hawk County, Iowa, United States. As of the 2000 census, its population was 941.
Union Township covers an area of 18.27sqmi and contains no incorporated settlements. According to the USGS, it contains three cemeteries: Finchford, Finchford Cemetey and Gerholdt.