Joseph Latham was deeded the land that includes present-day Dover in 1713, from portions of land that had been purchased from Native Americans by the Proprietors of West Jersey. On May 31, 1722, Latham and his wife Jane deeded 527 acres (2.13 km2) over to John Jackson of Flushing, New York. Jackson settled on the eastern portion of his land along Granny's Brook at the site of what would later become the Ross Ribbon Factory on Park Heights Avenue.
Iron ore at the time was so plentiful that it could be collected off the ground at the nearby Dickerson Mine in Mine Hill. At Jackson's Forge, ore would be processed into bars that would then be transported to Paterson and other industrial areas towards the east. The passage of the Iron Act by the British Parliament led to financial difficulties, leading Jackson into bankruptcy in 1753, with all of his property and belongings sold off at a Sheriff's sale. Quaker Hartshorne Fitz Randolph purchased Jackson's property and annexed to his own existing property, which would later become part of Randolph Township.
Dover was incorporated as a town on April 1, 1869, within Randolph Township and became fully independent as of March 5, 1896. The town charter was amended in 1875. On May 7, 1896, Dover was reincorporated as a city and regained its status as a town on March 21, 1899, after the referendum that approved the change was invalidated by a court ruling.
In its past, Dover has had extensive iron and mill works, machine shops, stove, furnace, and range works, boiler and bridge works, rolling mills, drill works, knitting and silk mills, and a large hosiery factory (MacGregors). During this period, Dover was a port on the Morris Canal while it was operational; the boat basin was located at what is today the JFK Commons Park.
Sources attribute the town's name to Dover, England or Dover, New Hampshire.