Westerheim Township was organized in 1876, and derives its name from a Norwegian-language word meaning "western home".

[3] According to the United States Census Bureau, the township has a total area of 36.3 square miles (94.1 km2), of which 36.3 square miles (94.1 km2) is land and 0.03% is water.

As of the census[1] of 2000, there were 286 people, 97 households, and 78 families residing in the township.

17.5% of all households were made up of individuals, and 5.2% had someone living alone who was 65 years of age or older.

About 3.7% of families and 9.0% of the population were below the poverty line, including 12.4% of those under the age of eighteen and none of those 65 or over.