Mullica Hill is a census-designated place and unincorporated community within Harrison Township in Gloucester County, in the U.S. state of New Jersey. As of the 2020 United States census, the CDP's population was 4,698, an increase of 716 from the 3,982 counted at the 2010 U.S. census, which in turn reflected an increase of 2,324 from the 1,658 enumerated at the 2000 census.