Four fire engines and around 25 firefighters attended a fire on Orsett Terrace in Woodford.
Part of a maisonette flat situated on the ground and first floors of a four-storey building was damaged by fire. There were no reports of any injuries.
The Brigade received the first of four calls at 0011 and Control Officers mobilised crews from Woodford, Walthamstow, Hainault and Chingford fire stations to the scene. The fire was extinguished by 0101.
The cause of the fire is under investigation by the Brigade and Metropolitan Police.