Four fire engines and 21 firefighters and officers were called to a fire at two garages in Brangbourne Road in Bromley in the early hours of Monday morning.
One garage was completed damaged by fire and a second garage sustained some fire damage. An adjacent hedgerow and fence were also completely gutted by the blaze.
One man left the premises before the arrival of the Brigade and he was treated at the scene for smoke inhalation by London Ambulance Service crews.
The Brigade was called at 0232 and the fire was under control at 0425. Fire crews from Bromley, Forest Hill, Lewisham and Woodside fire stations attended the scene.
The cause of the fire is believed to be due to a discarded cigarette igniting rubbish.