Ten fire engines and around 70 firefighters tackled a blaze at a house on Chelsfield Hill in Orpington.
Most of a detached house was destroyed by the fire and part of the roof was also damaged. There were no reports of any injuries.
Station Commander Clive Robinson, who was at the scene, said: "Crews worked extremely hard to bring this large fire under control.
"The fire created a lot of smoke and we advised people in the nearby area to keep their windows and doors shut."
The Brigade was called at 0217 and the fire was under control by 0622. Fire crews from Orpington, Biggin Hill, Bromley and surrounding fire stations were at the scene.
The cause of the fire is under investigation.