The fire broke out around 6:35 p.m. on Saturday at the Quality Inn on Britannia Road East near Hurontario Street, according to police.
A woman was found in the unit where the fire began and was transported to hospital, where she was pronounced dead.
Police say the fire happened in a single room. The cause of the fire is unknown at the moment.
Police also say they are treating the incident as suspicious until the fire marshal determines the cause.
The coroner and the fire marshal's office were called to the scene.