A resident said they saw the air ambulance circling above Turnpike Lane waiting for a space to land to treat the victim.
They added: “The officer on the cordon confirmed that the stabbing happened elsewhere and the victim made it to the parade of shops on Westbury Avenue before collapsing.”
A Met spokesman said: “Police were called by the London Ambulance Service at 12:48hrs on Monday, 30 May to reports of a man stabbed in the area of Westbury Road, N22.
“Officers attended. A man was found suffering from stab and slash injuries.
“Emergency services remain in attendance.
“There have been no arrests.”