CCTV footage, shared on X, shows the man rushing into the restaurant in Walm Lane at around 9pm on April 1.
Just moments later, he attempts to barricade the glass door shut, but the attacker forces his way in and shoves him to the ground.
He is then seen attacking the man several times with the knife, before pausing and beginning to film half way through.
The knifeman stabs and kicks the victim before another man enters the restaurant and manages to take him away.
Officers say the victim was driving his car when he was followed by a suspect in another vehicle.
It is believed that a crash took place, and the man ran into the restaurant where he was stabbed.
The victim then took himself to hospital where his injuries were assessed as non life-threatening.
No arrests have been made as police enquiries into the circumstances continue.
A spokesperson for Metropolitan Police said: “Police were called at around 9.06am on Tuesday, 1 April, to reports of a stabbing inside a restaurant in Walm Lane, Willesden.
“A man in his 20s then self-presented to hospital with stab wounds. His condition is not life-threatening or life-changing.
“It is believed the victim was driving his car when he was followed by the suspect in another vehicle.
“A collision took place and the victim ran into the restaurant where he was stabbed.
“No arrests have been made at this time but officers continue to follow all available lines of enquiry.”
