1804 in Australia
- Monarch - George III
- 4 March – The Castle Hill convict rebellion, also known as the Battle of Vinegar Hill, takes place: 200 convicts, mostly Irish, rebel. Fifty-one convicts are punished, and nine hanged.
- 3 May – An Aboriginal food hunting party is attacked by settlers and soldiers at Risdon Cove. Eyewitness estimates of the death toll from the massacre vary from three or four to fifty.
- 16 September – A government-owned brewery is opened at Parramatta as a means of controlling the consumption of spirits.
- 4 November – In a letter to Sir Joseph Banks, Matthew Flinders recommends that the newly discovered country, New Holland, be renamed "Australia" or "Terra Australis" (from the Latin "australis" meaning "of the south").
Exploration and settlement
- 15 February – Lieutenant-Governor David Collins lands at Risdon Cove in Van Diemen's Land (Tasmania). Unhappy with the area as a site for a settlement, Collins sends his surveyor, George Prideaux Harris, and harbour master William Collins in search of an alternative site. Harris and Collins recommend Sullivan's Cove.
- 24 March – The settlement at the Hunter River, also known as the Coal River, is officially named Newcastle.
- 8 May – Lieutenant-Governor Collins establishes the settlement at Sullivan's Cove on the Derwent River.
- 15 June – The name "Hobart Town", after the Colonial Secretary Lord Hobart, is adopted as the name for the new colony at Sullivan's Cove.
- 5 November – Lieutenant-Colonel William Paterson arrives at Outer Cove, leading the Buffalo, the Lady Nelson and two schooners, under instructions from London to form a settlement in the north of Van Diemen's Land.
- 5 October – Robert Campbell, politician (died 1859)
- Whitaker, Anne-Maree: Castle Hill convict rebellion 1804, Dictionary of Sydney.
- Darby, Andrew: Debate exposes 200-year-old massacre, The Age, 4 May 2004.
- Late in the eighteenth century, Australian Beers.
- Flinders' letter to Sir Joseph Banks 1804, National Library of Australia, 4 November 1804.
- Newman, Terry: Bowen Refuses to Bow Out, Parliamentary History Project (Parliament of Tasmania), December 2003.
- Settlement at Coal Harbour and Hunter’s River to be named Newcastle, Limits of Settlement and Governorship, &c., University of Newcastle, 24 September 1804.
- 1803–1850s, British outpost, Tasmanian Year Book 2005, Australian Bureau of Statistics, 21 November 2006.