The Frederick G. Gardiner Expressway, commonly known as the Gardiner Expressway or simply the Gardiner, is a partially at grade and elevated municipal expressway in Toronto, Ontario, Canada. Running close to the shore of Lake Ontario, it extends from the foot of the Don Valley Parkway (DVP) in the east, just past the mouth of the Don River, to the junction of Highway 427 and the Queen Elizabeth Way (QEW) in the west, for a total length of 18.0 kilometres (11.2 mi). East of Dufferin Street to just east of the Don River, the roadway is elevated for a length of 6.8 kilometres (4.2 mi), unofficially making it the longest bridge in Ontario, as it runs above Lake Shore Boulevard east of Spadina Avenue. The Gardiner Expressway is wholly owned and operated by the Province of Ontario.

Lake Shore Boulevard is a major arterial road running along more than half of the Lake Ontario waterfront in the city of Toronto, Ontario, Canada. Prior to 1998, two segments of Lake Shore Boulevard were designated as part of Highway 2, with the highway following the Gardiner Expressway between these two sections.