Four fire engines and around 25 firefighters tackled a fire at a shop with flats above on Broadway in Bexleyheath.
An electrical room on the ground floor was damaged by fire. Around 23 people left the building before crews arrived and there were no reports of any injuries.
Fire crews from Bexley, Plumstead and East Greenwich stations attended the incident.
The Brigade was called at 1338 and the fire was under control by 1528.
The fire is believed to have been accidental and caused by an electrical fault.