Hobsons Bay is a small open bay in Victoria, Australia, and is the northernmost part of the larger Port Phillip Bay. Its western and eastern boundaries are marked by Point Gellibrand in Williamstown and Point Ormond in Elwood respectively, and defines the coastal margin of the Melbourne suburbs of Wiliamstown, Newport, Port Melbourne, Albert Park, Middle Park, St. Kilda West, St. Kilda and Elwood. The Yarra River flows into Hobsons Bay.

Hobsons Bay is named after William Hobson who led the surveying party in Port Philip Bay.

Beaches adjoining the bay are Sandridge Beach (in Port Melbourne), Port Melbourne Beach (in Port Melbourne), South Melbourne Beach (in Albert Park), West Beach (in St Kilda West) and St Kilda Beach (in St Kilda).

• City of Hobsons Bay
• Hobsons Bay Coastal Trail
• Melbourne and Hobson's Bay Railway Company