Demarest is a borough in Bergen County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 4,981, an increase of 100 from the 2010 census count of 4,881, which in turn reflected an increase of 36 from the 4,845 counted in the 2000 census. Located in the northeastern corner of New Jersey and its Gateway Region, Demarest is part of the New York City Metropolitan Area.