Four fire engines and around 25 firefighters tackled a fire at a takeaway shop on Coldharbour Lane in Hayes.
Part of the kitchen in a ground floor takeaway shop was damaged by fire. The extraction system running from the ground floor to the first floor was destroyed by the blaze. There were no reports of any injuries.
The alarm was raised when a member of staff from a neighbouring shop smelled burning and called 999.
The Brigade's Fire Investigators believe the fire was accidental and caused by cooking that was left unattended.
A London Fire Brigade spokesperson said: "Cooking should never be left unattended on the hob or grill - if you have to leave the kitchen then turn off the heat.
"We'd also like to remind restaurant and takeaway owners to make sure that they don't have dirty ducting.
"If you don't clean your extraction system regularly, you're at a greater risk of ducting fires."
The Brigade was called at 1121 and the fire was under control by 1209. Fire crews from Hayes, Southall and Hillingdon fire stations attended the scene.