“We suspect that it was the man who lived in the house,” said Gotland police spokesman Benny Melin.
The fire services were alerted to the incident at around 10pm on Sunday. When the first unit arrived at the scene, the house was already consumed by the fire. A rescue attempt by firemen wearing smoke-protection gear was called off because of the ferocity of the blaze, said the Swedish Rescue Services in a press statement.
The cause of the fire was still unclear on Christmas Day.
Most other fire incidents on Christmas Eve were small apartment fires or blazes in storerooms.
A television caught fire in a terraced house in Strängnäs at around 4pm, but nobody was injured and the fire was quickly put out.
Early on the morning of Christmas Eve, two people were taken to hospital after a fire in an apartment block in Hägersten in southern Stockholm. Both people suffered mild smoke injuries.
A few incidents were more serious, however. The day before Christmas Eve, one person found dead after a blaze in a house in Ekerö, west of Stockholm.
There are more house fires in Sweden around Christmas than at any other time. On average there are 31 domestic fire incidents a day in the country, but that rises to 46 a day on Christmas Eve, according to the Swedish Rescue Services Agency.
Burning candles account for 19 percent of Christmas fires.