2021 Miami Open – Women's singles

Defending champion Ashleigh Barty won the women's singles tennis title at the 2021 Miami Open after Bianca Andreescu retired from the final with the scoreline at 6–3, 4–0. Barty saved a match point en route to the title, in the second round against Kristína Kučová.

Barty and Naomi Osaka were in contention for the WTA No. 1 singles ranking. Barty retained the top ranking by winning the title after Osaka lost to Maria Sakkari in the quarterfinals, ending a 23-match winning streak dating to the 2020 Cincinnati Masters.

Seeds
All seeds received a bye into the second round. • 🇦🇺 Ashleigh Barty (champion)

• 🇯🇵 Naomi Osaka (quarterfinals)

• 🇷🇴 Simona Halep (third round, withdrew)

• 🇺🇸 Sofia Kenin (third round)

• 🇺🇦 Elina Svitolina (semifinals)

• 🇨🇿 Karolína Plíšková (third round)

• 🇧🇾 Aryna Sabalenka (quarterfinals)

• 🇨🇦 Bianca Andreescu (final, retired)

• 🇨🇿 Petra Kvitová (fourth round)

• Kiki Bertens (second round)

•  Belinda Bencic (third round)

• 🇪🇸 Garbiñe Muguruza (fourth round)

• 🇺🇸 Jennifer Brady (second round)

• 🇧🇾 Victoria Azarenka (fourth round)

• 🇵🇱 Iga Świątek (third round)

• 🇧🇪 Elise Mertens (fourth round)

• 🇬🇧 Johanna Konta (third round)

• 🇺🇸 Madison Keys (second round)

• 🇨🇿 Markéta Vondroušová (fourth round)

•  Petra Martić (second round)

• 🇰🇿 Elena Rybakina (third round)

• 🇪🇪 Anett Kontaveit (third round)

•  Maria Sakkari (semifinals)

• 🇩🇪 Angelique Kerber (third round)

• 🇺🇸 Alison Riske (withdrew)

• 🇰🇿 Yulia Putintseva (second round)

• 🇹🇳 Ons Jabeur (fourth round)

• 🇺🇸 Amanda Anisimova (third round)

• 🇺🇸 Jessica Pegula (fourth round)

• 🇷🇺 Ekaterina Alexandrova (third round)

• 🇺🇸 Coco Gauff (second round)

• 🇷🇺 Veronika Kudermetova (third round)

Seeds
• # 🇯🇵 Misaki Doi (first round)

• # 🇨🇦 Leylah Fernandez (first round)

• # 🇮🇹 Martina Trevisan (first round)

• # 🇧🇪 Kirsten Flipkens (qualifying competition, lucky loser)

• # Tamara Zidanšek (qualifying competition)

• # 🇷🇺 Varvara Gracheva (qualifying competition)

• # 🇷🇸 Nina Stojanović (qualified)

• # 🇮🇹 Jasmine Paolini (first round)

• # 🇨🇳 Zhu Lin (first round)

• # 🇨🇳 Wang Yafan (first round)

• # 🇸🇰 Viktória Kužmová (qualifying competition, retired)

• # 🇭🇺 Tímea Babos (qualifying competition)

• # 🇨🇿 Tereza Martincová (qualified)

• # 🇪🇸 Aliona Bolsova (qualified)

• # 🇮🇹 Sara Errani (first round)

• # 🇧🇪 Greet Minnen (qualifying competition)

• # 🇸🇰 Anna Karolína Schmiedlová (qualifying competition)

• # 🇮🇹 Elisabetta Cocciaretto (qualified)

• # 🇺🇸 Caty McNally (first round)

• # 🇫🇷 Océane Dodin (qualified)

• # 🇺🇸 Kristie Ahn (qualifying competition)

• # 🇩🇪 Anna-Lena Friedsam (qualifying competition)

• # 🇷🇺 Liudmila Samsonova (qualified)

• # 🇦🇺 Astra Sharma (first round)

Qualifiers
• # 🇺🇸 Hailey Baptiste

• # Mihaela Buzărnescu

• # 🇧🇬 Tsvetana Pironkova

• # 🇪🇸 Aliona Bolsova

• # 🇫🇷 Océane Dodin

• # 🇷🇺 Liudmila Samsonova

• # 🇷🇸 Nina Stojanović

• # 🇷🇸 Olga Danilović

• # 🇨🇿 Tereza Martincová

• # 🇸🇰 Kristína Kučová

• # 🇲🇽 Renata Zarazúa

• # 🇮🇹 Elisabetta Cocciaretto

Lucky loser

 * 1) 🇧🇪 Kirsten Flipkens