Florham Park is a borough in Morris County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 12,585, its highest decennial count ever and an increase of 889 from the 11,696 recorded at the 2010 census, which in turn reflected an increase of 2,839 from the 8,857 counted in the 2000 census. Florham Park was incorporated as a borough by an act of the New Jersey Legislature on March 9, 1899, from portions of Chatham Township.