The fire started at about 10:00 in the complex on Walter Hay Court in Rosyth, which contains about 30 retirement bungalows.
The Scottish Fire and Rescue Service said several people had been rescued and evacuated from the burning building.
Police said a body had been found within the property. An investigation was under way at the site.
John Mills, head of Fife Council's housing services, said: "We were alerted to an incident this morning at an address Walter Hay Court.
"Unfortunately the fire has resulted in the death of an occupant and our sympathies are with their family and friends at this sad time."
A Police Scotland spokeswoman said: "Police in Fife are investigating following a fatal fire at an address in Walter Hay Court, Rosyth.
"The incident happened around 10am on Friday, December 16, when a fire was reported. Police and emergency services attended, however a body was found within the property.
"Police are currently undertaking a joint examination of the circumstances with the Scottish Fire and Rescue Service. A report will be sent the procurator fiscal."
A man has died in a huge blaze at a sheltered housing complex in Fife.