Highway 427 is an 400-Series Highway in the Greater Toronto Area of Ontario, Canada, that runs from immediately south of the Queen Elizabeth Way/Gardiner Expressway (its exact southern terminus is Evans Avenue) in Toronto to Highway 7 in the north, in Vaughan. It is 21.3 km in length. It was inaugurated in 1972, but it had been known as Highway 27 between the QEW and Highway 401, and as the Airport Expressway between the 401 and Highway 409 prior to that.

The 427 is Ontario's second busiest freeway by volume, and has no less than 12 lanes between the QEW/Gardiner and the 401. It is a primary feeder route into Toronto Pearson International Airport. Much of the traffic coming from Highway 407/ETR, Highway 401 (eastbound), and the QEW/Gardiner uses the 427 for airport access, but it also serves the western portion of Etobicoke and the northeastern portion of Mississauga (specifically, the Malton area). It is also used as a bypass for traffic originating from downtown Toronto headed towards the western suburbs.

There is talk of expanding this route further north to at least Highway 89, and possibly as far north as Barrie, but no firm plans for such an extension have been put forward yet.

Lane Configurations from South to North

Interchanges from South to North

• No exit numbers are posted on Highway 427, although they may be when the highway is extended.

Proposed Interchanges from South to North (exit numbers assumed)

Reference

• History of Ontario's Kings Highways - Hwy 427