William Street is a suburban distributor and one of two major cross-streets in the central business district of Perth, Western Australia.

Commencing in western Mount Lawley, its route takes it through the Northbridge café and nightclub district as well as the CBD.

After 600 metres (2,000 ft) it reaches Vincent Street, and the southern edge of Mount Lawley.

[1] The Horseshoe Bridge takes the road between the Perth railway station and Yagan Square.

This is followed by Murray and Hay streets, which are pedestrian malls to the east; and then St Georges Terrace, which is a through-route for vehicular traffic.

One more block takes it to an intersection with Mounts Bay Road, to the west, and the Esplanade to east.

These lines were later sunk as part of the Perth City Link project but the bridge remains.

Since 2014, William Street now carries State Route 5 south of The Esplanade due to the Elizabeth Quay development.