North Wales Fire and Rescue Service (NWFRS) said three fire engines attended the incident at a property on Cybi Close in Holyhead at 9.13am.
Firefighters used four breathing apparatus, two hose reel jets, a thermal imaging camera and small tools to extinguish the blaze – which was out shortly after 11am.
A NWFRS spokesperson said there was “significant damage” caused to the house, but thankfully no one was hurt in the incident.
They added that the cause of the blaze was accidental.