Oxford Mountain is a ridge and summit in the New York–New Jersey Highlands, the northeastern part of the Appalachian Mountains, in Warren County, New Jersey. Its main peak reaches 955 feet and extends across Oxford, Washington, and Mansfield Townships. Sykes Gap separates it from nearby County House Mountain to the northeast. Beyond its modest height, the mountain has geographic importance as part of the watershed divide between Pohatcong Creek and the Pequest River.