Multiple calls were received into the Hampshire and Isle of Wight Fire and Rescue Service control room from neighbours reporting the whole property was alight.
The body of the man was found in the building and he was confirmed dead at the scene.
Firefighters used 20 sets of breathing apparatus, three jets, two hose reel jets and the aerial ladder platform to extinguish the fire.
Crews worked to isolate the electrics before withdrawing from the property due to a partial collapse of the building.
Once the fire was surrounded the incident was scaled down, with two fire engines remaining on the scene to dampen down any remaining hotspots.
Fire Investigation Officers have been on the scene to establish a cause.
HIWFRS crews delivered community safety materials, Safe and Well visits and reassurance messaging to neighbouring properties before leaving the scene following the stop message at 10:00.
Visit our website to find out how you can refer yourself or someone you know, for one of our free Safe and Well visits, tailored to an individual’s needs to help protect them in their home.