Her mother and three other children were also home at the time of the fire. They were taken to hospital with smoke inhalation but were not believed to be seriously injured.
Firefighters were called to the Hereford St property in Cannons Creek at 9.46am and the house was well ablaze by the time they arrived, station officer Gerald Twiss said.
Fire officers found the body of the girl in the lounge.
Two children, a toddler and a child over five, got out a window, and the mother was outside with the baby when firefighters arrived.
Mr Twiss said the fire engulfed the house "quickly" and, fanned by strong winds, was "totally involved" when the fire service arrived.
He said it was not believed to have involved fireworks despite occurring on Guy Fawkes Day.
"It's not known whether the house had smoke alarms, or whether they were working, but it is a reminder ... they are cheap insurance," Mr Twiss said.
Neighbour Tapu Matapuku, 15, said he was sleeping when the fire began and was woken by the smell.
"I looked outside and all I could see was smoke. I saw three or four kids run down the back (of the property)."
He said he went to the property and spoke with the mother, who was fearful her children may still be inside.
The house was "too hot" to enter and look for the children, he said.
By then the flames were "running around everywhere".
Mr Matapuku said there were older children who were away at school and the father was at work.
"The people are cool, they always ask us to come and play 'cause they've got a pool table in the garage."
He said the family moved into the house last year.
Police Inspector John Spence confirmed several older children were away at school.
He said it was a "very very sad" situation.
Seven fire appliances, ambulance, police, victim support and council hazard officers attended the scene.
Environmental Science and Research was checking the safety of the asbestos roof.
Fire safety officers and police will now investigate the cause of the blaze.
