The following lists events that happened during 1940 in Australia.

• Monarch – George VI
• Governor-General – Alexander Hore-Ruthven, 1st Baron Gowrie
• Prime Minister – Robert Menzies
• Chief Justice – Sir John Latham

• 28 February – The Australian 7th Division is formed.
• 16 March – A state election is held in Victoria. The Country Party led by Albert Dunstan is returned to government.
• 14 June – The Volunteer Defence Corps is formed, a militia force based on the British Home Guard.
• 6 July – The Story Bridge is opened in Brisbane.
• 19 July – The Australian cruiser HMAS Sydney takes part in the sinking of the Italian cruiser Bartolomeo Colleoni
• 1 August – The first of sixty Bathurst-class corvettes, HMAS Bathurst, is launched in Sydney.
• 13 August – An RAAF Lockheed Hudson crashes near Canberra, killing three members of Cabinet and the Chief of the General Staff.^[1]
• 3 September – The heavy cruiser HMAS Australia takes part in Operation Menace off Dakar.
• 6 September – The British prison ship HMT Dunera docks in Sydney, carrying refugees and prisoners of war considered a danger to British security, for internment in Hay and Tatura.
• 21 September – The 1940 federal election results in a hung parliament, with Prime Minister Robert Menzies remaining in office at the head of a minority government.
• 16 October – Country Party leader Archie Cameron resigns and is succeeded by Arthur Fadden as acting leader.
• 26 October – Double-decker buses replace the last cable trams in Melbourne.

• Max Meldrum wins the Archibald Prize with his portrait of Dr J Forbes McKenzie
• The Man Who Loved Children by Christina Stead is published.
• The Magic Basket a musical play for children by Alfred Wheeler is published

• Forty Thousand Horsemen, directed by Charles Chauvel and starring Chips Rafferty, is released

• Old Rowley wins the Melbourne Cup
• Beaulivre wins the Caulfield Cup
• Beau Vite wins the Cox Plate
• New South Wales wins the Sheffield Shield
• Eastern Suburbs win the 1940 NSWRFL season, defeating Canterbury-Bankstown 24–14. Western Suburbs finish in last place, claiming the wooden spoon.

• 5 January – Athol Guy, musician
• 19 January – Paul Calvert, Liberal Senator for Tasmania
• 17 February – Marilyn Jones, ballet dancer
• 22 February – Neil Brown, politician
• 24 February – Ian Shelton, Australian rules football player (died 2021)
• 27 February – Bill Hunter, actor (died 2011)
• 1 March – Robin Gray, Premier of Tasmania (1982–1989)
• 8 March – Don Barker, actor
• 19 March – Andrew Taylor, poet
• 20 March – Paul Neville, politician (died 2019)
• 12 April – Jack Hibberd, playwright
• 16 April – Marion Halligan, writer (died 2024)^[2]
• 24 April – Trevor Kent, actor (died 1989)
• 26 April – Ian Geoghegan, race car driver (died 2003)
• 15 June – Ken Fletcher, tennis player (died 2006)
• 17 June – Alan Murray, Australian golfer (died 2019)
• 23 June – Diana Trask, country music singer
• 25 June – Judy Amoore, athlete
• 29 June – Ken Done, artist
• 3 August – Judith Troeth, Liberal Senator for Victoria
• 16 August – Bruce Beresford, film director
• 18 August – Jan Owen, poet
• 31 August – Jack Thompson, actor
• 9 September – Hugh Morgan, businessman
• 13 September – Kerry Stokes, chairman of the Seven Network
• 15 September – Allan Andrews, NSW politician
• 21 September – John Pochee, jazz musician (died 2022)
• 3 October – Diana Warnock, radio broadcaster and politician
• 4 October – Ian Kiernan, environmentalist, 1994 Australian of the Year (died 2018)
• 5 October – Bob Cowper, cricketer
• 15 October – Peter C. Doherty, medical researcher, Nobel Prize recipient
• 19 October – Ian Causley, politician (died 2020)
• 21 October – Peter Arnison, Governor of Queensland (1997–2003)
• 1 November – John Bell, actor and theatre director
• 4 November – John Sanderson, Governor of Western Australia (2000–2005)
• 12 November – John Dowd, NSW politician
• 7 December – Robin Miller, aviator and nurse (died 1975)
• 19 December – Jane Mathews, judge (died 2019)

• 3 February – John Henry Michell, mathematician (b. 1863)
• 5 February – Bill Wilks, New South Wales politician (b. 1863)
• 8 March – Michael Kelly, Catholic archbishop (b. 1850)
• 16 April – Herbert James Carter, entomologist (b. 1858)
• 20 April – Sir Ernest Gaunt, naval admiral (b. 1865)
• 22 June – Monty Noble, cricketer (b. 1873)
• 23 June – Hugh Denis Macrossan, Queensland politician and judge (b. 1881)
• 6 July – Michael O'Connor, Western Australian politician (b. 1865)
• 22 July – Sir George Fuller, 22nd Premier of New South Wales (b. 1861)
• 27 July – Bluey Wilkinson, speedway rider (b. 1911)
• 30 July
  • Arthur Merric Boyd, painter (b. 1862)
  • Archibald Watson, surgeon and professor of anatomy (b. 1849)
• 13 August
  • James Fairbairn, Victorian politician (b. 1897)
  • Henry Gullett, Victorian politician (b. 1878)
  • Geoffrey Street, Victorian politician (b. 1894)
  • Sir Brudenell White, 10th Chief of the General Staff (b. 1876)
• 9 September – Percy Abbott, New South Wales politician (b. 1869)
• 11 September – Issy Smith, soldier and Victoria Cross recipient (b. 1890)
• 22 September – Robert Blackwood, New South Wales politician (b. 1861)
• 2 October – Albert Green, Western Australian politician (b. 1869)
• 14 October – Helen de Guerry Simpson, novelist (b. 1897)
• 25 October – Thomas Waddell, 15th Premier of New South Wales (b. 1854)
• 31 October
  • Frank Anstey, Victorian politician (born in the United Kingdom) (b. 1865)
  • John Keating, Tasmanian politician (b. 1872)
• 2 November – Colin Rankin, Queensland politician and soldier (b. 1869)
• 3 November – James Fowler, Western Australian politician (born in the United Kingdom) (b. 1863)
• 23 November – Sir Stanley Argyle, 32nd Premier of Victoria (b. 1867)
• 11 December – Belle Golding, feminist, suffragist and labour activist (b. 1864)
• 20 December – Tom Foster, composer (b. 1870)

• List of Australian films of the 1940s