Four fire engines and around 25 firefighters tackled a flat fire on Upper Gulland Walk in Islington.
Half of the third floor of a split-level flat was damaged by fire. There have been no reports of any injuries.
The Brigade was called at 1009 and the fire was under control by 1059. Fire crews from Homerton, Holloway and Soho fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and Metropolitan Police Service.