Four fire engines and around 25 firefighters were called to a fire at an office block on Church Road in Leyton.
Part of the first floor of an office block was damaged by fire. There were no reports of any injuries.
The fire was discovered by a neighbour who called the Brigade.
The Brigade was called at 0102 and the fire was under control by 0235. Fire crews from Leyton, Walthamstow and Leytonstone fire stations attended the scene.
The fire is under investigation by the Brigade and the Metropolitan Police Service.