The city’s homicide unit says a stray bullet from a shooting outside a building in the Martha Eaton Way and Trethewey Drive area entered the boy’s room at around 12:30 a.m.
The boy was rushed to hospital, where he was pronounced dead.
Police say stray bullets also entered two other building units and no one else was injured.
Investigators say it is too early to describe the possible suspects.
Toronto police say the shooting is a cowardly act and they are asking witnesses to come forward.