The Watchung Mountains are a pair of two long low ridges of volcanic origin, between 400 ft. (122 m) and 500 ft. (152 m) high, lying end-to-end in northern New Jersey in the United States. The ridges, known as First Watchung Mountain (south) and Second Watchung Mountain (north), stretch for approximately 40 miles (64 km) from Somerville in the southwest to Paterson in the northeast. Collectively, the two ridges demarcate a geologic barrier on the western edge of the plains west of the Hudson River. The highest point in the Watchungs is High Mountain in Wayne, New Jersey, which is over 1,000 ft. tall. Other notable summits are Garrett Mountain in Paterson and the Hilltop in Verona. The Hilltop is the highest point in Essex County. All along the Watchungs there are country reservations.

The mountains have historically been the site of extensive quarrying of basalt. Since the 1970s, the area has seen extensive suburban growth, but before the construction of the interstate highways, the Watchungs actually held back urbanization.