The 2020 census found 4,277 people in the township.

Located in the northern part of the county, it borders the following townships: No municipalities are located in Marlboro Township, although the unincorporated community of Marlboro is located in the township's east.

Statewide, the only other Marlboro Township is located in Delaware County.

Marlboro Township was historically also spelled Marlborough.

In 1833, Marlborough Township contained three stores, one tannery, and four saw mills.