New Jersey Transit (usually shortened to NJ Transit or NJT) is a New Jersey State-owned public transportation system serving the US state of New Jersey; along with portions of New York, Orange, and Rockland counties in New York State; and Philadelphia County in Pennsylvania. It operates bus, light rail, and commuter rail services throughout the state, notably connecting to major commercial and employment centers both within the state and in the adjacent major cities of New York and Philadelphia.

Covering a service area of 5,325 square miles (13,790 km²), NJT is the largest statewide public transit system and the third largest provider of bus, rail, and light rail transit by ridership in the United States, linking major points in New Jersey, New York, and Pennsylvania.

NJT also acts as a purchasing agency for many private operators in New Jersey, with numerous private operators receiving equipment from NJT (primarily buses) for route service within the state not controlled by NJT.