North Middletown is an unincorporated community and census-designated place within Middletown Township, in Monmouth County, in the U.S. state of New Jersey. As of the 2020 census, the CDP population was 3,146, down from 3,295 in 2010. The community was formerly known as East Keansburg and was renamed North Middletown by municipal ordinance around 1988.