The blaze at a terraced house in Upper Bennett Street, off Abercorn Road in Derry, was reported shortly after 8.00am.
The man was found dead at the scene by emergency services.
Emergency Services attended but unfortunately the man was found deceased at the scene.
Police say an investigation into the cause of the fire “has now commenced.”
SDLP MLA Pat Ramsey has appealed to anyone with information to help in the investigation,
Mr Ramsey said the local community had been shocked by the tragedy.
He said: “The very tragic death of this man over night in a fire is very shocking and upsetting not only for the man’s family and friends but also for his neighbours and wider community. I would like to express my sympathies and condolences.
“I understand that the PSNI will be investigating the circumstances of this terrible incident and I would urge anyone with any information to help in that investigation.”