Five ships of the Royal Australian Navy have been named HMAS Sydney, after Sydney, the capital city of New South Wales.
- HMAS Sydney (1912), a Town-class light cruiser launched in 1912, decommissioned in 1928, and broken up for scrap
- HMAS Sydney (D48), a Leander-class light cruiser launched in 1934, and sunk following a battle with the German auxiliary cruiser Kormoran on 19 November 1941
- HMAS Sydney (R17), a Majestic-class light aircraft carrier launched in 1944, decommissioned in 1973, and broken up for scrap
- HMAS Sydney (FFG 03), an Adelaide-class guided missile frigate launched in 1980, and decommissioned in 2015
- HMAS Sydney (DDG 42), a Hobart-class air warfare destroyer in service since 2020