Marlboro Township is a township in Monmouth County, in the U.S. state of New Jersey. The township is located within the Raritan Valley region and is a part of the New York Metropolitan Area. As of the 2020 United States census, the township's population was 41,502, an increase of 1,311 (+3.3%) from the 2010 census count of 40,191, which in turn reflected an increase of 5,449 (+16.3%) from the 33,423 counted in the 2000 census.

Marlboro Township was formed by an act of the New Jersey Legislature on February 17, 1848, from portions of Freehold Township. The township was named for the marl beds found in the area.