Four fire engines and around 25 firefighters tackled a fire in a garden on Ashmore Grove in Welling.
A shed in the rear garden was destroyed and a small part of the roof of a garage with solar panels was damaged by the fire.
The fire was accidental and is believed to have been caused by a bonfire burning out of control.
Assistant Commissioner Thomas Goodall said: "London is already facing its second heatwave of the year and we know that people will be looking forward to getting outside to enjoy the wonderful weather. But the high temperatures and low rainfall in recent months means the current risk of wildfires is severe.
“We’re strongly advising people to avoid burning any waste in this type of weather and to not have bonfires, particularly in their gardens.”
"If you must have a bonfire, never leave it unattended and consider your neighbours if you do decide to have a fire in your garden.
"Make sure you build it clear of buildings, garden sheds, fences and hedges and never use flammable liquids to start it or burn dangerous items such as aerosol cans. Always keep a bucket of water or a hosepipe nearby in case of fire.
“Always check your local authority’s advice on bonfires and follow our safety tips."
One of the Brigade’s 32-metre turntable ladders was used at the scene as an observation tower to provide the Incident Commander with an aerial view of the fire.
Control Officers took the first of 26 calls at 1734 and mobilised crews from Bexley, East Greenwich and Lee Green fire stations to the scene. The incident was over for firefighters at 1930.