The 1925 Australasian Championships was a tennis tournament that took place on outdoor Grass courts at the White City Tennis Club, Sydney, Australia from 24 January to 31 January. It was the 18th edition of the Australian Championships (now known as the Australian Open), the 4th held in Sydney, and the first Grand Slam tournament of the year. The singles titles were won by Australians James Anderson and Daphne Akhurst.
See main article: 1925 Australasian Championships – Men's singles. 
James Anderson defeated Gerald Patterson 11–9, 2–6, 6–2, 6–3
See main article: 1925 Australasian Championships – Women's singles. Daphne Akhurst defeated Esna Boyd 1–6, 8–6, 6–4
See main article: 1925 Australasian Championships – Men's doubles. Pat O'Hara Wood / Gerald Patterson defeated James Anderson / Fred Kalms 6–4, 9–7, 7–5
See main article: 1925 Australasian Championships – Women's doubles. Daphne Akhurst / Sylvia Harper defeated Esna Boyd / Kathleen Le Messurier 6–4, 6–3
See main article: 1925 Australasian Championships – Mixed doubles. Daphne Akhurst / Jim Willard defeated Sylvia Harper / Bob Schlesinger 6–4, 6–4