See main article: 2004 Australian Open.
Justine Henin-Hardenne defeated Kim Clijsters in the final, 6–3, 4–6, 6–3 to win the women's singles tennis title at the 2004 Australian Open. It was her third major title, each time defeating Clijsters in the final (after her victories at the 2003 French and US Opens). Clijsters would eventually win the title seven years later.
Serena Williams was the reigning champion, but did not participate this year due to a left knee injury.
Fabiola Zuluaga became the first Colombian to reach a major semifinal.
See main article: 2004 Australian Open – Women's singles qualifying.
| Category |  Henin-Hardenne | Clijsters | |
|---|---|---|---|
| 1st serve % | 38/77 (49%) | 60/91 (66%) | |
| 1st serve points won | 31 of 38 = 82% | 37 of 60 = 62% | |
| 2nd serve points won | 17 of 39 = 44% | 11 of 31 = 35% | |
| Total service points won | 48 of 77 = 62.34% | 48 of 91 = 52.75% | |
| Aces | 4 | 1 | |
| Double faults | 6 | 6 | |
| Winners | 31 | 37 | |
| Unforced errors | 38 | 43 | |
| Net points won | 14 of 18 = 78% | 14 of 28 = 50% | |
| Break points converted | 6 of 8 = 75% | 4 of 6 = 67% | |
| Return points won | 43 of 91 = 47% | 29 of 77 = 38% | |
| Total points won | bgcolor=98FB989 | 91 | 77 |
| Source | |||