Route 33 begins in Trenton on a two-lane road. It passes through central Mercer County, joining northbound US 130 in Robbinsville Township. It leaves the U.S. highway in East Windsor and becomes a local town road into the borough of Hightstown. It turns east again as it passes the east end of the Hightstown Bypass, where it becomes a divided arterial with four lanes as it makes its way through Monmouth County toward the shore. Around Freehold, it becomes a freeway. It then crosses the Garden State Parkway's Exit 100 in Tinton Falls and Route 18 in Neptune. Here, it is locally known as Corlies Avenue. Route 33 ends at Route 71 in Neptune. It has two concurrencies along the route, one with Route 34 and the second with US 130.