Two occupants at the property situated off Cannock Wood Street, Hazelslade, discovered the blaze after being woken up by a smoke alarm at about 12.30am a week ago.
Staffordshire Fire and Rescue Service said it was urging residents to take care when using candles and particularly late at night due to the risks.
The brigade stated: "The cause of the fire has been confirmed as accidental due to a candle being left unattended inside the property.
"The occupiers had fallen asleep and were alerted through a smoke alarm, where they attempted to extinguish the fire themselves before recognising that the conditions were too severe.
"They had already left the property as a result when our crews arrived."
"A woman was administered oxygen at the scene due to smoke inhalation and was later taken by ambulance to Walsall Manor Hospital. A man was also taken to hospital for precautionary checks.
"They were both discharged from hospital later that morning," the service stated.
Two crews based at Cannock tackled the flames and smoke at the premises near Rugeley Road out the first floor fire within 30 minutes of arriving at the scene on October 1.
One room was severely damaged by the fire with some heat damage extending further into other parts of the property which was left completely smokelogged.
The service added: "We would ask members of the community to be extremely careful if using candles in their home, especially if doing so late at night.
"Although significant damage to the property was caused the presence of a working fire alarm had alerted the occupants who were able to bring themselves to safety.
"In the event of a fire we would always advise people not to try tackling it themselves, but to leave the property via the nearest available exit and to call 999."