The fire broke out around 5 a.m. Friday in a three-storey apartment building on De Chambly St. near Sherbrooke St. East.
Jean Leblanc, chief of operations for the Montreal fire department, said the woman in her 50s died before they arrived.
“There was nothing that could have been done. She was already dead,” Leblanc said.
The building was evacuated, but residents will be able to return later today, he said.
The Montreal police arson squad is investigating.