Five fire engines and around 30 firefighters tackled a fire at a residential block of flats on Baring Street in Islington.
A two-roomed flat on the first floor of the eight-storey building was mostly damaged by fire. There were no reports of any injuries.
The Brigade was called at 0548 and the fire was under control by 0651. Crews from Islington, Shoreditch, Whitechapel and surrounding fire stations attended the scene.
The cause of the fire is under investigation.