Fairfield Township is a township in Crow Wing County, Minnesota, United States. The population was 275 at the 2000 census.
According to the United States Census Bureau, the township has a total area of 35.9 square miles (93 km2), of which 33.5 square miles (87 km2) is land and 2.4 square miles (6.2 km2) (6.57%) is water.