The London Fire Brigade was alerted to the blaze in Stanstead Road with the first of nine calls just before 5.40am on March 2.
Six fire engines and around 40 firefighters from stations across Forest Hill, Lewisham and Greenwich were dispatched to the scene.
Half of the three roomed flat was damaged in the blaze.
A man had managed to escape the building before the arrival of the fire brigade and was taken to hospital by the London Ambulance Service.
The fire was under control by 6.38am and an investigation is ongoing.
The Metropolitan Police arrested a man in his 40s on suspicion of arson with the intent to danger life.
A fire brigade spokesperson said: “Six fire engines and around 40 firefighters tackled a fire at a semi detached house on Stanstead Road in Catford.
RELATED: Man arrested on suspicion of arson after fire at home in Catford
“Half of a three roomed flat on the ground floor was damaged by the fire. One man left the building before the Brigade arrived and was taken to hospital by London Ambulance Service.
“Control Officers took the first of nine calls at 0538 on Sunday morning and mobilised crews from Forest Hill, Lewisham, Greenwich and surrounding fire stations to the scene. The fire was under control by 0638.
“The cause of the fire is under investigation.”
