The blaze occurred in the Waterside on Sunday evening. It is not being treated as suspicious.
Police confirmed this morning that the man died following a fire at a house in the Clooney Terrace area.
Police were notified of the fire just before 5pm, and attended along with colleagues from other emergency services.
Inspector Lavery said: “Northern Ireland Fire & Rescue Service extinguished the blaze but, sadly, a man was pronounced dead at the scene.
“Police are conducting enquiries into this death, on behalf of the Coroner. At this stage, the death is not being treated as suspicious.”
A Northern Ireland Fire & Rescue Service spokesperson said: “The thoughts and sympathies of Northern Ireland Fire & Rescue Service are with the family and friends of a man who died following a fire on Clooney Terrace, Derry/ Londonderry.
“On Sunday, September 12 at 4.54pm, Firefighters were called to reports of a fire in a flat on Clooney Terrace, Derry/Londonderry.
“Four Fire Appliances attended the incident- 1 from Northland, 2 from Crescent Link and 1 from Limavady.
“On arrival, attending crews were faced with a well-developed fire within the flat which required Firefighters wearing Breathing Apparatus to enter the property to extinguish the fire.
“Tragically, a male casualty was discovered in the property and was pronounced dead at the scene.
“The fire was under control by 6:18pm and the cause remains under investigation.”
DUP MLA Gary Middleton said: "Deeply saddened to hear that a gentleman has died following the incident at Clooney Terrace, Waterside last night. My deepest sympathies are with his family and friends at this sad time."
UUP Alderman Darren Guy said: "Saddened to hear of the death of a man in Clooney Terrace house fire on Sunday evening. My thoughts and condolences are with the family at this sad time."