Marenisco Township is a civil township of Gogebic County in the U.S. state of Michigan. The population was 455 at the 2020 census, a significant decrease from 1,727 at the 2010 census.
The unincorporated community of Marenisco is within the township on the Presque Isle River near the junction of U.S. Highway 2 and M-64 at . Wakefield is about northwest, and Watersmeet about southeast on US 2.
The name was formed by combining the first three letters of the first, middle, and last names of Mary Enid Scott, the wife of E. H. Scott, a timber producer.
According to the United States Census Bureau, the township has a total area of , of which is land and 15.0 square miles (38.9 km or 4.61%) is water. It is the second-largest township in land area in Michigan (after McMillan Township in Luce County).
The climate is described as Humid Continental by the Köppen Climate System, abbreviated as Dfb.
As of the census of 2000, there were 1,051 people, 264 households, and 186 families residing in the township. In 2020, there were 455 people in the township.