Union Township is one of twelve townships in Hendricks County, Indiana, United States. As of the 2010 census, its population was 1,856.

Union Township covers an area of 24.05 square miles (62.3 km); of this, 0.01 square miles (0.026 km) or 0.05 percent is water.

• Lizton

• Montclair
• Raintown

(This list is based on USGS data and may include former settlements.)

• Harrison Township, Boone County (northeast)
• Middle Township (east)
• Center Township (south)
• Eel River Township (west)
• Jackson Township, Boone County (northwest)

The township contains nine cemeteries: Burgess, Cundiff, Groover, Leach Number 1, Leach Number 2, Lizton K of P, Montgomery, Pritchett and Vieley.

• Interstate 74
• U.S. Route 136
• Indiana State Road 39

• U.S. Board on Geographic Names (GNIS)
• United States Census Bureau cartographic boundary files