Four fire engines and around 25 firefighters tackled a fire at a restaurant with flats above on Plashet Road in Plaistow.
Parts of the ground-floor kitchen and the ducting between the ground and first floors of the two-storey building were damaged by fire. Five people left the building before the arrival of the Brigade, and there are no reports of any injuries.
The fire is believed to have been accidental and caused by a build up of cooking oil within the ducting.
A London Fire Brigade spokesperson said: "We'd like to remind restaurant and takeaway owners to ensure they don't have dirty ducting. If you don't clean the ducting in your extraction system regularly, you're at a greater risk of ducting fires.
"You should also make sure you keep the hob, cooker hood and extractor fan clean too – built up fat and grease can ignite and cause a fire."
The Brigade was called at 0756 and the fire was under control by 0843. Crews from Plaistow, Stratford, East Ham and Leytonstone fire stations attended the scene.