Around 2:50am the victim was in his blue Citroen Berlingo in North Road when a man approached and threatened him with the weapon.
The driver was forced from his vehicle and the suspect stole the car and personal items and drove off.
The 46-year-old driver was uninjured, but left badly shaken by the incident.
The suspect is described as white, around 5’8”–5’10” tall, of thin build and spoke with a local accent.
He was wearing a black, hooded zip top and dark coloured tracksuit trousers, which had white stripes down the arms and legs.
The vehicle was recovered a short time later in Blairholm Drive, and officers are checking CCTV for any additional information which could assist their enquiries.
Detective Constable Gary Lipscombe said: “I am appealing to anyone who was in the area in the early hours of this morning to contact us as they may have information which could help us trace the suspect.
“Any small piece of information could be relevant in our enquiries so please do pass it on. I would also appeal to motorists for any dash cam images as they may have captured the suspect on their footage.”
Anyone with information is asked to contact CID officers at Wishaw via 101, or alternatively call Crimestoppers on 0800 555 111 in confidence.