The Jersey Fire and Rescue service was called to the property in Hilary Street at around 9.30 pm on Friday following reports of a fire on the fourth floor of a block of flats.
Neighbours had been alerted after a smoke alarm went off.
The property was filled with smoke but firefighters using breathing apparatus quickly found a person unconscious inside and took them to safety.
A team of on-call firefighters were then called in to help put the blaze out.
In a statement Jersey Fire and Rescue said: ‘The casualty was taken to hospital by ambulance for further assessment and treatment, although the extent of any injuries is not known. An investigation is underway to identify the cause of this fire.’
