2015 US Open – Women's singles

Flavia Pennetta defeated Roberta Vinci in the final, 7–6(7–4), 6–2 to win the women's singles tennis title at the 2015 US Open. It was her first and only major singles title, and she became the first woman to win her first major title after turning 30 years old. Pennetta was competing in her 49th major main draw, setting a new record for the most appearances in major main draws before reaching a final. This also marked Pennetta's last major appearance, as she retired from the sport at the end of the 2015 season. Vinci became the first unseeded woman to reach a major final since Justine Henin at the 2010 Australian Open. The final made Italy the fifth country in the Open Era to have two countrywomen contest a major final (after Australia, the United States, Belgium, and Russia). This also marked the first final with two first-time major finalists since the 2010 French Open.

Serena Williams was the three-time defending champion, but lost in the semifinals to Vinci. Williams was attempting to become the fourth woman (after Maureen Connolly, Margaret Court and Steffi Graf) to complete the Grand Slam. She was also attempting to win an Open Era record seventh US Open singles title. Williams' defeat to Vinci is regarded by some as one of the greatest upsets in tennis history.

This was the major main draw debut of future Australian Open champion, Sofia Kenin, who lost to Mariana Duque Mariño in the first round.

Petra Kvitová became the first player born in the 1990s to reach the quarterfinals at all four singles majors.

Seeds
• 🇺🇸 Serena Williams (semifinals)

• 🇷🇴 Simona Halep (semifinals)

• 🇷🇺 Maria Sharapova (withdrew because of a right leg injury)

• Caroline Wozniacki (second round)

• 🇨🇿 Petra Kvitová (quarterfinals)

• 🇨🇿 Lucie Šafářová (first round)

• 🇷🇸 Ana Ivanovic (first round)

• 🇨🇿 Karolína Plíšková (first round)

• 🇪🇸 Garbiñe Muguruza (second round)

• 🇪🇸 Carla Suárez Navarro (first round)

• 🇩🇪 Angelique Kerber (third round)

•  Belinda Bencic (third round)

• 🇷🇺 Ekaterina Makarova (fourth round)

•  Timea Bacsinszky (first round)

• 🇵🇱 Agnieszka Radwańska (third round)

• 🇮🇹 Sara Errani (third round)

• 🇺🇦 Elina Svitolina (third round)

• 🇩🇪 Andrea Petkovic (third round)

• 🇺🇸 Madison Keys (fourth round)

• 🇧🇾 Victoria Azarenka (quarterfinals)

• 🇷🇸 Jelena Janković (first round)

• 🇦🇺 Samantha Stosur (fourth round)

• 🇺🇸 Venus Williams (quarterfinals)

• 🇩🇪 Sabine Lisicki (fourth round)

• 🇨🇦 Eugenie Bouchard (fourth round, withdrew because of a concussion)

• 🇮🇹 Flavia Pennetta (champion)

• 🇫🇷 Alizé Cornet (first round)

•  Irina-Camelia Begu (first round)

• 🇺🇸 Sloane Stephens (first round)

• 🇷🇺 Svetlana Kuznetsova (first round)

• 🇷🇺 Anastasia Pavlyuchenkova (second round)

• 🇸🇰 Anna Karolína Schmiedlová (third round)