2009 WTA Tour Championships – Singles

Serena Williams defeated the defending champion, her sister Venus Williams, in the final, 6–2, 7–6(7–4) to win the singles title at the 2009 WTA Tour Championships. It was her second Tour Finals singles title.

Caroline Wozniacki and Victoria Azarenka made their debuts at the event.

Dinara Safina and Serena Williams were in the contention of year-end no. 1 ranking. Williams secured the year-end no. 1 ranking for the second time when Safina withdrew from the tournament.

Players
• # 🇷🇺 Dinara Safina (round robin, retired/withdrew due to a back injury)

• # 🇺🇸 Serena Williams (champion)

• # 🇷🇺 Svetlana Kuznetsova (round robin)

• # Caroline Wozniacki (semifinals, retired due to a left abdominal strain)

• # 🇷🇺 Elena Dementieva (round robin)

• # 🇧🇾 Victoria Azarenka (round robin, retired due to cramping)

• # 🇺🇸 Venus Williams (final)

• # 🇷🇸 Jelena Janković (semifinals)

Alternates
• # 🇷🇺 Vera Zvonareva (replaced Safina) (round robin, withdrew due to ankle injury)

• # 🇵🇱 Agnieszka Radwańska (replaced Zvonareva) (round robin)

White group
''Standings are determined by: 1. number of wins; 2. number of matches; 3. in two-players-ties, head-to-head records; 4. in three-players-ties, percentage of sets won, or of games won; 5. steering-committee decision.''

Maroon group
''Standings are determined by: 1. number of wins; 2. number of matches; 3. in two-players-ties, head-to-head records; 4. in three-players-ties, percentage of sets won, or of games won; 5. steering-committee decision.''