The man was struck by the white Peugeot 205 on Queen’s Road shortly after 9.30 am.
He was treated at the scene by paramedics before being transferred to hospital.
The driver was arrested on suspicion of driving without due care and attention and while unfit through drink or drugs.
The accident caused major traffic disruption, with the road being closed for several hours.
In a separate accident at about 9.30 am on Monday, a 61-year-old motorcyclist was injured in a collision with a truck at the junction of Bagot Road and Plat Douet Road.
The rider was taken to hospital and discharged about an hour and a half later.
