Incumbents

• Monarch King George VI
• Governor-General Alexander Hore-Ruthven, 1st Baron Gowrie (until 30 January), then the Duke of Gloucester
• Prime Minister John Curtin (died in office 5 July), then Frank Forde (until 13 July), then Ben Chifley

State Premiers

• Premier of New South Wales William McKell
• Premier of Queensland Frank Cooper
• Premier of South Australia Thomas Playford IV
• Premier of Tasmania Robert Cosgrove
• Premier of Victoria Albert Dunstan (until 2 October), then Ian MacFarlan (until 21 November), then John Cain
• Premier of Western Australia John Willcock (until 31 July), then Frank Wise

State Governors

• Governor of New South Wales John Loder, 2nd Baron Wakehurst (until 6 June)
• Governor of Queensland Sir Leslie Orme Wilson
• Governor of South Australia Sir Charles Norrie
• Governor of Tasmania Sir Ernest Clark (until 4 August), then Sir Hugh Binney (from 24 December)
• Governor of Victoria Sir Winston Dugan
• Governor of Western Australia none appointed

Events

• 30 January Prince Henry, Duke of Gloucester becomes Australia's first royal Governor-General.
• 9 May Germany surrenders to the Allies, ending World War II in Europe.
• 26 June Dr H. V. Evatt signs the United Nations Charter on behalf of Australia.
• 5 July Prime Minister John Curtin dies in office from heart problems at The Lodge in Canberra.
• 6 July Frank Forde is sworn in as Prime Minister of Australia, following the death of John Curtin. He will serve Australia's shortest term as Prime Minister, being replaced by Ben Chifley a week later.
• 7 July The Australian 7th Division commences operations in the Battle of Balikpapan. Operations are completed by 21 July.
• 13 July Ben Chifley is elected as leader of the Australian Labor Party, becoming the 16th Prime Minister of Australia.
• 15 August Japan surrenders to the Allies, ending World War II. The day is known as V-P Day (Victory in the Pacific).
• 10 November A general election is held in Victoria.

Science and technology

• 12 December Howard Florey shares the Nobel Prize in Physiology or Medicine for his work on penicillin.

Arts and literature

• William Dargie wins the Archibald Prize with his portrait of Edmund Herring
• Russell Drysdale painted The Drover's Wife

Film

• 1 May The Australian National Film Board is established.

Sport

• 1 September Eastern Suburbs defeats Balmain 22 18 in the final of the 1945 New South Wales Rugby Football League season.
• 29 September The 1945 VFL Grand Final is held, and becomes known as the "Bloodbath" due to the wet, muddy conditions and frequent violence between players and amongst the spectators. Carlton defeats South Melbourne 15.13 (103) to 10.15 (75).
• 6 November Rainbird wins the Melbourne Cup.
• 26 December The first Sydney to Hobart Yacht Race begins. The British yacht Rani wins both line honours and the handicap, arriving in Hobart on 3 January.

Births

• 1 January Peter Duncan, politician
• 2 January Diane Fahey, poet
• 2 January Byron Lamont, botanist
• 8 January Jeannie Lewis, musician
• 10 January John Fahey, Premier of New South Wales (1992 1995)
• 15 January John Peard, rugby league player and coach
• 19 January Judith Clingan, composer and musician
• 22 January Arthur Beetson, rugby league player and coach
• 22 January Ken Ticehurst, politician
• 26 January John Coates, mathematician
• 11 February Ralph Doubell, Olympic athlete
• 23 February Robert Gray, poet
• 26 February Peter Brock, racing driver (died 2006)
• 3 March George Miller, film director and producer
• 16 March Michael Cobb, politician
• 10 April Kevin Berry, butterfly swimmer (died 2006)
• 13 April Judy Nunn, actress
• 8 May Janine Haines, politician (died 2004)
• 17 May Tony Roche, tennis player
• 22 May Bob Katter, politician
• 29 May Chris Barrie, Chief of the Defence Force
• 2 June Michael Leunig, cartoonist.
• 5 July Johnny Famechon, boxer
• 8 July Graeme Blundell, actor
• 13 July Ashley Mallett, cricketer
• 17 July Athena Starwoman, astrologer
• 18 July Max Tolson, soccer player
• 21 July Geoff Dymock, cricketer
• 1 August Ken Aldred, politician
• 2 August Alex Jesaulenko, Australian rules football player
• 7 August Graham Ramshaw, Australian rules football player
• 12 August Mal Washer, politician
• 18 August Gillian Bouras, writer
• 27 August Kerry O'Brien, television journalist
• 25 October Peter Ledger, illustrator (died 1994)
• 26 October John Romeril, playwright
• 1 November John Williamson, singer
• 15 November Roger Donaldson, New Zealand film director
• 19 November Barry Haase, politician
• 26 November Roger Price, politician
• 28 November John Hargreaves, actor
• 5 December Joanne Burns, poet
• 15 December Thaao Penghlis, actor
• 22 December Sam Newman, Australian rules football player and media personality
• 31 December Vernon Wells, actor

Deaths

• 28 January Samuel Dennis (born 1870), politician
• 4 March Harry Chauvel (born 1865), soldier
• 5 March Rupert Downes (born 1885), soldier
• 15 April Tom Collins (born 1884), politician
• 5 June Albert Piddington (born 1862), High Court judge
• 5 July John Curtin (born 1885), Prime Minister of Australia (1941 1945)
• 29 July Henry Burrell (born 1873), naturalist
• 20 August Sir Macpherson Robertson (born 1859), confectioner
• 6 December Sir Edmund Dwyer-Gray (born 1870), Premier of Tasmania (1939)