| Champ: |  Anett Kontaveit |
| Runner: |  Ekaterina Alexandrova |
| Score: | 4–6, 6–4, 7–5 |
| Draw: | 28 |
| Seeds: | 8 |
| Before Year: | 2019 |
See main article: article and 2021 Kremlin Cup.
Belinda Bencic was the defending champion, having won the previous edition in 2019,[1] but she withdrew before the tournament began.
Anett Kontaveit won the title, defeating Ekaterina Alexandrova in the final, 4–6, 6–4, 7–5.
The top four seeds received a bye into the second round.