At right, toy dinosaurs have been left by visitors. Plaques at the Hadrosaurus Foulkii Leidy Site showing National Historic Landmark status (left) and a plaque from Philadelphia's Academy of Natural Sciences. Arrowheads and pottery shards have been found by residents by the banks of the Cooper River, hinting that there was a Native American settlement in Haddonfield at one point in time. The Lenape disappeared from the local area when settlers arrived. The Haddonfield area was occupied by Lenni Lenape Native Americans. The borough was named for Elizabeth Haddon, an early settler of the area. The borough became an independent municipality in 1894.

Haddonfield was incorporated by an act of the New Jersey Legislature on April 6, 1875, within portions of Haddon Township following a referendum on the same day. As of the 2020 United States census, the borough's population was 12,550, an increase of 957 (+8.3%) from the 2010 census count of 11,593, which in turn reflected a decline of 66 (−0.6%) from the 11,659 counted in the 2000 census Haddonfield is a borough located in Camden County, in the U.S.

Haddon township