There were no reports of injuries among the 71 people aboard.
Authorities say Flight 5124 landed around 6:20 p.m. on Monday, shortly after the pilot was approaching the airport to land as scheduled and noticed a landing gear problem.
Newark fire-fighters were called to the scene, but found no smoke or fire aboard the plane.
A spokesman for the Port Authority of New York and New Jersey says the airport was closed shortly after the landing. Two of the airport's three runways reopened about an hour later.
Additional details were not immediately available.