Police and Fire and Emergency New Zealand (Fenz) investigators have completed their examination of the scene in Phillips St, Kensington.
An autopsy had also been completed, a police spokeswoman said.
A probable cause of the fire had been identified, but police were not immediately able to share the results, as further tests had yet to be completed, she said.
The fire was not being treated as suspicious, police confirmed.
Police could not yet release the name of the deceased.
Firefighters were notified of the blaze about 10.10pm on Friday and five crews attended the incident, Fenz has said.