Five fire engines and around 30 firefighters tackled a fire at a takeaway, with homes above, on Dyne Road in Kilburn.
Most of a ground floor takeaway and all of the ducting from ground to first floor was damaged by the fire.
People were advised to avoid the area if possible, including Kilburn High Road whilst the incident was ongoing.
The cause of the fire is believed to have been accidental and involved a deep fat fryer.
A London Fire Brigade spokesperson said: "There are a number of steps you can take to reduce the fire risks.
"Take extra care when cooking with hot oil as it can easily overheat and catch fire. Never fill a pan more than one third full of fat or oil and make sure food is dry before putting it in hot oil – oil and water are a dangerous mix. If the oil starts to smoke, it’s too hot so turn off the heat and leave it to cool. We also advise using an electronic deep fat fryer if possible – they have automatic temperature controls, and are much safer.
"It's also really important to keep the hob, cooker hood and extractor fan clean too – built up fat and grease can ignite and cause a fire."
The Brigade's 999 Control Officers received 17 calls about the fire.
The Brigade was called at 1617 and the incident was over for firefighters at 1720. Firefighters from West Hampstead, Willesden, Paddington and North Kensington fire stations attended the scene.