High Road in Willesden was closed for hours on Monday (July 7) after the knife attack at around 11.53am.
Officers were called to reports of a man with a knife threatening a member of staff in a shop near the Pound Village store.
A man, 30, was found with a slash injury to his face and he was treated at the scene before being taken to hospital.
His injuries are not life-threatening, police have said.
No arrests have been made at the moment, but police continue to investigate.
The road began to reopen to the public at around 5pm.
A Metropolitan Police spokesperson said: “Police were called at 11:53hrs on Monday, 7 July to reports of a man with a knife threatening a member of staff in a shop in High Road, Willesden Green NW10.
“Officers and the London Ambulance Service attended and found a 30-year-old man suffering a slash injury to his face.
“He was treated at the scene before being taken to hospital. His injuries are not life-threatening.
“No arrests have been made at this stage and enquiries continue.”
Anyone with information is asked to call police on 101 or message @MetCC on X quoting CAD 3149/7JUL. Alternatively contact Crimestoppers anonymously on 0800 555 111.
