It happened shortly after 17:00 GMT at a ground-floor flat on the corner of Ardoyne Road and Glenbryn Drive.
The fire, which caused significant damage, is believed to have started in a bedroom of the flat, but it is unclear how it was started.
Police cordoned off the area around the property and forensic officers examined it on Friday night.
A neighbour on the first floor had to escape through an upstairs window.
It is understood she was treated for minor injuries.
Neighbours also reported seeing four people running away from the flat at the time the fire was reported.
It is not clear if the ground-floor property was occupied when the fire took place.
In a separate, unconnected incident, a 52-year-old man was rescued from a fire at a house on Reid Street off the Cregagh Road in east Belfast.
Both fires are now under control.
Police are treating a fire at a property in north Belfast as suspected arson.