Four fire engines and around 25 firefighters tackled a fire on Warton Road in Stratford.
Half of a second-floor flat in a four-storey residential building was damaged by fire. There were no reports of any injuries.
The Brigade's 999 Control Officers received nine calls about the fire.
The Brigade was called at 1843 and the fire was brought under control by 1936. Crews from Stratford, Leytonstone, Plaistow and Leyton fire stations attended the scene.
The cause of the fire is under investigation by the Brigade and Metropolitan Police.