Union Township is one of twelve townships in Floyd County, Iowa, United States. As of the 2000 census, its population was 682.

According to the United States Census Bureau, Union Township covers an area of 41.16 square miles (106.59 square kilometers); of this, 40.78 square miles (105.63 square kilometers, 99.1 percent) is land and 0.37 square miles (0.97 square kilometers, 0.91 percent) is water.

• Marble Rock

• Aureola at 42°58′06″N 92°52′41″W / 42.968304°N 92.877972°W / 42.968304; -92.877972

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

• Ulster Township (north)
• Saint Charles Township (northeast)
• Pleasant Grove Township (east)
• Dayton Township, Butler County (southeast)
• Coldwater Township, Butler County (south)
• Bennezette Township, Butler County (southwest)
• Scott Township (west)
• Rockford Township (northwest)

The township contains these three cemeteries: Hillside, Westside and St. Mary's Catholic, Roseville, Iowa.

• Iowa Highway 14

• Shell Rock River

• Greene Community School District
• Rudd-Rockford-Marble Rock Community School District

• Iowa's 4th congressional district
• State House District 14
• State Senate District 7

• United States Census Bureau 2008 TIGER/Line Shapefiles
• United States Board on Geographic Names (GNIS)
• United States National Atlas

• US-Counties.com
• City-Data.com