Two cars collided on Picton Road, a key route connecting Wollongong and Sydney, before 6.30am, according to a statement from NSW Police.
The crash left both drivers trapped. The driver of one vehicle, identified by authorities as a man in his late teens, was treated by paramedics but died at the scene. The other driver, a 26-year-old man, was taken to Liverpool Hospital with head and leg injuries in a serious but stable condition.
Picton Road was closed in both directions for most of Saturday morning. Transport for NSW advised motorists travelling between Sydney and Wollongong to use the Hume Motorway or Appin Road. The road had reopened by midday.
Police are investigating the crash and said a report would be prepared for the state coroner. They are urging anyone with dashcam footage or other information to contact Camden Police Area Command or Crime Stoppers.
There have been at least four fatal crashes on Picton Road since 2022, including a collision that year between a car and a truck that claimed the life of a 54-year-old man.