Const. Fiona Thivierge said police were called to the scene on Derry Road, near Mavis Road, at about 3:30 a.m. on Sunday.
Police say the vehicle was headed east along Derry Road, toward John Watt Boulevard, when it left the roadway for unknown reasons and struck the light standard.
"This is an absolutely tragic accident with devastating effects," Thivierge told CBC News.
The victim was pronounced dead at the scene.
Thivierge said the victim was a 19-year-old woman from Brampton, Ont. Her family has been notified of her death.
The crash remains under investigation by the major collision bureau.
Thivierge said "speed is definitely a factor" in the deadly crash. Toxicology tests will determine if alcohol was a factor as well.
Police are looking to speak with witnesses. Anyone with information can call 905-453-3311 and ask to be put through to the major collision bureau.