Piasa Township is one of eleven townships in Jersey County, Illinois, United States. As of the 2010 census, its population was 3,376 and it contained 1,321 housing units.

According to the 2010 census, the township has a total area of 36.1 square miles (93 km), of which 35.99 square miles (93.2 km) (or 99.70%) is land and 0.11 square miles (0.28 km) (or 0.30%) is water.

• Brighton (western portion)

• Lake Piasa

• Fidelity Township (north)
• Shipman Township, Macoupin County (northeast)
• Brighton Township, Macoupin County (east)
• Foster Township, Madison County (southeast)
• Godfrey Township, Madison County (south)
• Mississippi Township (west)
• Jersey Township (northwest)

The township contains these five cemeteries: Botts, Edwards, Eldridge, Marston and Saint Alphonsus.

• U.S. Route 67
• Illinois Route 267/111

• Thunderbird Lake

Historical population

Census	Pop.	Note	%±
2016 (est.)	3,193
U.S. Decennial Census

• Jersey Community Unit School District 100
• Southwestern Community Unit School District 9

• Illinois' 19th congressional district
• State House District 97
• State Senate District 49

• "Piasa Township, Jersey County, Illinois". Geographic Names Information System. United States Geological Survey, United States Department of the Interior. Retrieved January 17, 2010.
• United States Census Bureau 2007 TIGER/Line Shapefiles
• United States National Atlas

• City-Data.com
• Illinois State Archives