Four fire engines and around 25 firefighters tackled a fire at a restaurant with dwellings above on Kilburn High Road.
There were no reports of any injuries.
A small electrical fire occurred in an overheated fan due to dirty 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."
Control Officers took the first of seven calls at 2000 and mobilised crews from West Hampstead, Willesden and Paddington fire stations to the scene. The incident was over for firefighters at 2126.
Firefighters' top tips for restaurants and takeaways: