Marcy Township is one of seventeen townships in Boone County, Iowa, USA. As of the 2000 census, its population was 1,137.
Marcy Township was organized in 1858. It is named for William L. Marcy.
Marcy Township covers an area of 42.06 square miles (108.9 km2) and contains no incorporated settlements. According to the USGS, it contains seven cemeteries: Glenwood, Holloway, Oakwood, Pleasant Hill, Quincy, Sparks and Swede Valley Lutheran.