Westlake Avenue is also served by a variety of public transit routes, including the South Lake Union Streetcar and RapidRide C Line.

Westlake Avenue begins at Stewart Street on the north side of McGraw Square, which also serves as the southern terminus of the South Lake Union Streetcar.

[3] The southernmost block of Westlake Avenue is divided between the streetcar tracks and a southbound-only street that connects to a porte-cochère for the Westin Seattle hotel complex.

Westlake gains a northbound lane after crossing 6th Avenue and continues northwest across the Denny Triangle street grid, forming several triangular blocks.

[12] Lake Union became a landing point for coal shipments that were hauled by boat and wagon from modern-day Newcastle and Renton and were bound for ships on Elliott Bay.

[12][15] Westlake Avenue is served by the South Lake Union Streetcar, which began operating in 2007, and several bus routes run by King County Metro.

[23] The southern reaches of Westlake have been criticized by cyclists due to the presence of streetcar tracks that pose a danger to thinner bicycle tires.