The incident happened outside the Highgate Hill branch at around 1.15am today (December 1).
London Ambulance Service attended and a person was taken to hospital “as a priority”.
McDonald’s outside Archway station is currently closed by the police.
LIVE updates as McDonald’s in Islington closed by police after stabbing
Blood stains are visible on the floor of the store alongside debris and a first aid kit.
A spokesperson for the London Ambulance Service said: “We were called at 1.18am today (1 December) to reports of a stabbing on Highgate Hill, Islington.
“We sent resources to the scene, including an ambulance crew, a paramedic in fast response car, a clinical team manager and an incident response officer.
“We treated a patient and took them to hospital as a priority.”
We have contacted the Metropolitan Police and McDonald’s UK for comment.
