Middletown Township is a township in northern Monmouth County, in the U.S. state of New Jersey. As of the 2020 United States census, the township was the state's 20th-most-populous municipality and the largest in the county, with a population of 67,106, an increase of 584 (+0.9%) from the 2010 census count of 66,522, which in turn reflected an increase of 195 residents (0.3%) from its population of 66,327 in the 2000 census, when it was the state's 17th-most-populous municipality.

Monmouth County is a county, located in the central section of the U.S. state of New Jersey. Comprising much of the northern half of the Jersey Shore, it is bordered to its west by Mercer and Middlesex Counties, to its south by Ocean County, to its east by the Atlantic Ocean, and to its north by the Raritan Bay. Monmouth County's geographic area comprises 30% water. The county is considered part of the Central Jersey region of the state, though it was not among the four counties explicitly listed as included in Central Jersey as part of legislation signed into law in 2023.