The incident occurred on June 17 around 12:30 p.m. at Kipling Station, near Kipling Avenue and Dundas Street. Police say a man allegedly poured a flammable liquid on a female passenger while on a bus and then set the substance on fire.
The woman, who was in her 20s, was rushed to hospital with second and third degree burns.
Police confirmed to CP24 that the woman has died. The homicide unit has now taken over the investigation.
A 33-year-old man identified as Toronto resident Tenzin Norbu has previously been charged with attempted murder and assault with a weapon in connection with the incident. At the time, police also said they were treating the case as a suspected hate crime, although no further details were released.
The charges have not been proven in court and it is not yet clear if they will change now that the victim has died.
Police said the attack was an isolated incident and that the victim and suspect were not known to each other.