The victim was in a coma when she was brought to Kwong Wah Hospital, where she was later certified dead.
Police said the blaze prompted three other tenants to dash for safety.
A witness at the scene said Choi had lived at a subdivided flat on the ninth floor.
A neighbour in the flat next door said they called police after seeing thick smoke coming out of Choi’s room.
It was not immediately clear where the fire started.
Police have said they are still investigating the incident.
The Fire Services Department said a preliminary investigation suggested the case of the fire was not suspicious.
According to official figures, more than 215,700 people are currently living in subdivided flats in Hong Kong.
Additional data shows about 127,900 households are in the queue for a public housing flat, with the average waiting time currently standing at 5.7 years.