A fire broke out in a prison hospital cell at Wandsworth Prison in Heathfield Road just before 6pm on Wednesday.
The blaze took around 20 minutes to extinguish.
The prisoner inside the cell was treated for smoke inhalation but did not require hospital care.
Thanks to the prison’s ventilation system, no other inmates were affected or had to be evacuated.
A Prison Service spokesperson said: “A small cell 1 at HMP Wandsworth was quickly extinguished by prison staff. The fire brigade attended as a matter of routine and there were no reported injuries.”
Originally published by UKNIP.