Kim Clijsters defeated Justine Henin-Hardenne in the final, 7–5, 6–1 to win the women's singles tennis title at the 2005 Canadian Open.
Amélie Mauresmo was the defending champion, but lost in the semifinals to Henin-Hardenne.
The top eight seeds received a bye into the second round.
Maria Sharapova (withdrew due to a right pectoralis muscle strain)
Amélie Mauresmo (semifinals) Svetlana Kuznetsova (third round)
Justine Henin-Hardenne (final)
Serena Williams (third round, withdrew due to left knee pain) Nadia Petrova (quarterfinals, retired due to a right pectoralis strain) Kim Clijsters (champion) Mary Pierce (withdrew due to a right thigh strain) Anastasia Myskina (semifinals) Nathalie Dechy (second round)
Daniela Hantuchová (first round, retired due to heat illness)
Flavia Pennetta (quarterfinals) Dinara Safina (second round) Tatiana Golovin (second round)
Ai Sugiyama (second round)