2021 Kremlin Cup – Women's singles

Belinda Bencic was the defending champion, having won the previous edition in 2019, but she withdrew before the tournament began.

Anett Kontaveit won the title, defeating Ekaterina Alexandrova in the final, 4–6, 6–4, 7–5.

Seeds
The top four seeds received a bye into the second round. • #🇧🇾 Aryna Sabalenka (quarterfinals)

• #🇪🇸 Garbiñe Muguruza (quarterfinals)

• # Maria Sakkari (semifinals, retired)

• #🇷🇺 Anastasia Pavlyuchenkova (quarterfinals)

• #🇹🇳 Ons Jabeur (first round, retired)

• #🇩🇪 Angelique Kerber (withdrew)

• #🇰🇿 Elena Rybakina (first round)

• #🇷🇴 Simona Halep (quarterfinals)

• #🇪🇪 Anett Kontaveit (champion)

Seeds
• # 🇺🇸 Bernarda Pera (qualified)

• # 🇷🇺 Kamilla Rakhimova (first round)

• # 🇷🇴 Irina Bara (qualifying competition, lucky loser)

• # 🇧🇬 Viktoriya Tomova (first round)

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

• # 🇷🇺 Vitalia Diatchenko (qualifying competition)

• # 🇷🇺 Anastasia Gasanova (first round)

• # 🇷🇸 Aleksandra Krunić (qualified)

• # 🇺🇦 Lesia Tsurenko (qualified)

• # 🇮🇹 Lucia Bronzetti (first round)

• # 🇷🇺 Anna Kalinskaya (qualified)

• # 🇦🇺 Arina Rodionova (first round)

Qualifiers
• # 🇺🇸 Bernarda Pera

• # 🇷🇺 Oksana Selekhmeteva

• # 🇨🇳 Zheng Qinwen

• # 🇷🇸 Aleksandra Krunić

• # 🇺🇦 Lesia Tsurenko

• # 🇷🇺 Anna Kalinskaya

Lucky loser
• # 🇷🇴 Irina Bara