The incident is believed to have happened at around 1.30 am on Saturday morning in the New Lodge Road area.
The victim, who had also received facial injuries, was rushed to hospital for treatment.
His condition is described as critical but stable.
Detective Sergeant Corrigan of the PSN’s Criminal Investigation Branch said: “We are currently working to establish the exact circumstances of this incident.
“I would appeal to anyone who was in this area, around 1.30 am and saw what happened, to get in touch with us on the 101 number.”
Alternatively, information can be passed anonymously to Crimestoppers on freephone 0800 555 111.