Mount Olive Township is a township in western Morris County, in the U.S. state of New Jersey. As of the 2020 United States census, the township's population was 28,886, its highest decennial census count ever and an increase of 769 (+2.7%) from the 2010 census count of 28,117, which in turn reflected an increase of 3,924 (+16.2%) from the 24,193 counted in the 2000 census.