1840 in Australia

Incumbents

• Monarch - Victoria

Governors

• Governor of New South Wales – Sir George Gipps
• Governor of South Australia – Lieutenant Colonel George Gawler
• Governor of Tasmania – Captain Sir John Franklin
• Governor of Western Australia as a Crown Colony – John Hutt

Events

• 3 January – The Melbourne newspaper The Herald is founded by George Cavenagh as The Port Phillip Herald.
• 13 January – The Battle of Yering occurs between Indigenous Australians of the Wurundjeri nation and the Border Police.
• March – Between 40 and 60 Jardwadjali Aboriginal people are killed in the Fighting Hills massacre. The Whyte brothers William, George, Pringle and James Whyte, cousin John Whyte and three convict employees, Benjamin Wardle, Daniel Turner and William Gillespie were responsible.
• April – Up to 60 Jardwadjali Aboriginal people are killed in the Fighting Waterholes massacre. The Whyte brothers William, George, Pringle and James Whyte and their employees were responsible.
• May – British Government agrees to cease sending convicts to New South Wales, some 80,000 convicts had been sent since 1788. Convicts still sent to Van Diemen's Land and Port Phillip District colonies.
• 30 June – survivors of the Maria shipwreck are massacred by Aboriginal Australians on the Coorong.
• 25 August – Two Ngarrindjeri men are hanged on the Coorong in front of their tribe after being convicted in a drumhead court-martial of the murders of all 26 crew and passengers of the Maria shipwreck, Major Thomas O'Halloran, South Australian Police Commissioner, presiding and passing sentence.
• 11 October – the Lettsom raid in Melbourne, the mass-arrest and imprisonment of approximately 400 Wurundjeri, Woiworrung, Boonwurrung and Taungurung people.
• 2 November – Construction of The Causeway across the Swan River in Perth begins.
• Undated – Sydney City Council and Adelaide City Council are incorporated. A ratepayer required £1,000 worth of property to stand for election.
• Undated – An unknown number of Indigenous Australians are murdered by Angus McMillan's men at Nuntin and at Boney Point as part of a series of mass murders of Gunai Kurnai people known as the Gippsland massacres.
• Undated – Aboriginals Fire Arm Regulation Act 1840 is enacted prohibiting 'Aboriginal Natives' of New South Wales from possessing fire arms or ammunition without the permission of a Magistrate.

Births

• 3 February – Allan McLean, 19th Premier of Victoria
• 11 March – Ralph Tate, botanist and geologist
• 26 April – Paddy Hannan, prospector
• 23 May – George Throssell, 2nd Premier of Western Australia
• 4 November – William Giblin, 13th Premier of Tasmania
• 8 December – William Guilfoyle, landscape gardener and botanist
• Unknown – Tommy Windich, explorer

Deaths

• 28 January – Simeon Lord, merchant and magistrate
• 17 November – Henry Fulton, chaplain and writer
• 24 December – Thomas Moore, settler