William Street is a major street in the Melbourne central business district, Victoria, Australia. It runs roughly north–south from Flinders Street to Victoria Street, and was laid out in 1837 as part of the original Hoddle Grid. The street is located in-between King Street and Queen Street.

Notable landmarks on William Street include the Queen Victoria Market, the Flagstaff Gardens, Immigration Museum, Supreme Court of Victoria, AMP Square, Australian Club and 140 William Street.

Several buildings and structures on William Street are listed on the Victorian Heritage Register and/or classified by the National Trust of Australia. These include:

• 140 William Street
• Australian Club Building
• Court of Appeal
• Goldsborough Mort Building
• Hume House
• Prometheus Mural in Monash House
• Queensland Building
• Royal Melbourne Mint (former)
• Royal Standard Hotel
• Scottish House
• Shell Corner (former)
• Supreme Court of Victoria
• Western House

William Street's junction with Lonsdale Street forms the legal precinct of Melbourne.^[5] This junction is the location of the Supreme Court of Victoria, Melbourne Magistrates' Court and County Court. The Federal Court building, housing the High Court and other Federal courts, is located one block further north on the corner of William Street and La Trobe Street. The Law Institute of Victoria is located one block south of Lonsdale Street at the corner of Bourke Street.

Flagstaff railway station is situated on William Street. Besides that, William Street is also served by a tram route. Tram route 58 runs along William Street between Peel Street and Flinders Lane.

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