New Jersey State Highway 166 is a state highway in New Jersey, United States. Like many state highways in New Jersey, it was created when a U.S. highway (in this case, U.S. 9) was rerouted.

NJ 166's northern end is at an intersection with U.S. 9 and the Garden State Parkway in Dover, New Jersey. It runs through South Toms River, New Jersey and Beachwood, New Jersey before terminating at an intersection with U.S. 9 in Beachwood.