The crash occurred at the junction of Malone Road and Stranmillis Road on Monday at around 8.30am.
He was rushed by ambulance to the Royal Victoria Hospital, Belfast for treatment to head injuries.
A Belfast Trust spokesperson confirmed on Monday afternoon that the man was in a critical condition.
A 19-year-old woman was also taken to hospital for treatment for non life threatening injuries.
Police are appealing for anyone with information to come forward.