| Singles | |
|---|---|
| 2021 Rancho Santa Fe Open | |
| Champion |  Rebecca Peterson |
| Runner-up |  Elvina Kalieva |
| Final score | 6–4, 6–0 |
You Xiaodi was the defending champion [1] but chose not to participate.
Rebecca Peterson won the title, defeating Elvina Kalieva in the final, 6–4, 6–0.
Rebecca Peterson (Champion)
Fiona Ferro (Semifinals, retired) Madison Brengle (Semifinals)
Zarina Diyas (Second round)
Misaki Doi (First round)
Kristína Kučová (Quarterfinals)
Renata Zarazúa (First round)
Polona Hercog (Quarterfinals)| Semifinals | Final | ||||||||||||
| 1 | Rebecca Peterson | 6 | 6 | ||||||||||
| 3 | Madison Brengle | 4 | 2 | ||||||||||
| 1 | Rebecca Peterson | 6 | 6 | ||||||||||
| Q | Elvina Kalieva | 4 | 0 | ||||||||||
| Q | Elvina Kalieva | 4 | 6 | 3 | |||||||||
| 2 | Fiona Ferro | 6 | 4 | 0r | |||||||||
| First Round | Second Round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | R Peterson | 6 | 6 | ||||||||||||||||||||||||
| WC | H Chang | 1 | 0 | 1 | R Peterson | 6 | 6 | ||||||||||||||||||||
| M Hibi | 6 | 6 | M Hibi | 1 | 1 | ||||||||||||||||||||||
| Q | M Partaud | 3 | 3 | 1 | R Peterson | 6 | 6 | ||||||||||||||||||||
| Q | A Krueger | 2 | 2 |  L Cabrera | 4 | 1 | |||||||||||||||||||||
| SE | E Bektas | 6 | 6 | SE | E Bektas | 6 | 1 | 65 | |||||||||||||||||||
| L Cabrera | 6 | 6 | L Cabrera | 4 | 6 | 77 | |||||||||||||||||||||
| 7 | R Zarazúa | 2 | 2 | 1 | R Peterson | 6 | 6 | ||||||||||||||||||||
| 3 | M Brengle | 6 | 6 | 3 | M Brengle | 4 | 2 | ||||||||||||||||||||
| WC | A Kiick | 0 | 2 | 3 | M Brengle | 6 | 6 | ||||||||||||||||||||
 R Marino | 6 | 6 | R Marino | 1 | 2 | ||||||||||||||||||||||
| M Inglis | 4 | 3 | 3 | M Brengle | 4 | 6 | 6 | ||||||||||||||||||||
 K Kozlova | 7 | 6 | K Kozlova | 6 | 1 | 4 | |||||||||||||||||||||
| Q | T Mihalíková | 5 | 2 | K Kozlova | 2 | 6 | 6 | ||||||||||||||||||||
| WC | K Day | 3 | 6 | 6 | WC | K Day | 6 | 3 | 2 | ||||||||||||||||||
| 5 | M Doi | 6 | 4 | 3 | |||||||||||||||||||||||
| First Round | Second Round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 8 | P Hercog | 65 | 6 | 7 | |||||||||||||||||||||||
| WC | J Failla | 77 | 3 | 5 | 8 | P Hercog | 6 | 6 | |||||||||||||||||||
| Q | E Douglas | 77 | 3 | 6 | Q | E Douglas | 4 | 2 | |||||||||||||||||||
| Q | M Manasse | 64 | 6 | 2 | 8 | P Hercog | 4 | 3 | |||||||||||||||||||
| Q | D Hewitt | 5 | 6 | 2 | Q | E Kalieva | 6 | 6 | |||||||||||||||||||
| Q | E Kalieva | 7 | 1 | 6 | Q | E Kalieva | 6 | 2 | 6 | ||||||||||||||||||
 L Küng | 0 | 1 | 4 | Z Diyas | 4 | 6 | 2 | ||||||||||||||||||||
| 4 | Z Diyas | 6 | 6 | Q | E Kalieva | 4 | 6 | 3 | |||||||||||||||||||
| 6 | K Kučová | 4 | 6 | 6 | 2 | F Ferro | 6 | 4 | 0r | ||||||||||||||||||
| JE | E Jacquemot | 6 | 4 | 2 | 6 | K Kučová | 1 | 77 | 77 | ||||||||||||||||||
| Q | H Giavara | 5 | 0 | PR | P Hon | 6 | 64 | 64 | |||||||||||||||||||
| PR | P Hon | 7 | 6 | 6 | K Kučová | 66 | 6 | 4 | |||||||||||||||||||
 K Kawa | 1 | 4 | 2 | F Ferro | 78 | 3 | 6 | ||||||||||||||||||||
| Ar Rodionova | 6 | 6 | Ar Rodionova | 2 | 2 | ||||||||||||||||||||||
| C Dolehide | 2 | 7 | 2 | 2 | F Ferro | 6 | 6 | ||||||||||||||||||||
| 2 | F Ferro | 6 | 5 | 6 | |||||||||||||||||||||||
Kurumi Nara was the defending champion, but chose to compete in Dubai instead.
Eugenie Bouchard was the defending champion, but chose not to participate this year.
Monica Niculescu was the defending champion, but she lost in the quarterfinals to Yanina Wickmayer.
Timea Bacsinszky was the defending champion, but chose to compete in Doha instead.
Louisa Chirico was the defending champion, but chose to participate in Stuttgart instead.
Elizaveta Kulichkova was the defending champion, but chose not to participate.
Lesia Tsurenko was the defending champion and successfully defended her title, defeating Stefanie Vögele in the final, 5–7, 7–6(7–2), 6–2.
Beatriz Haddad Maia was the defending champion, but chose to compete at the 2018 Mutua Madrid Open instead.
Garbiñe Muguruza was the defending champion, but lost in the second round to Lesia Tsurenko.
Danielle Collins was the defending champion, but chose not to participate as she was still competing at the Australian Open.
Madison Brengle was the defending champion but lost to Caty McNally in the quarterfinals.
Elina Svitolina was the two-time defending champion, but lost in the second round to Victoria Azarenka.
Aryna Sabalenka was the defending champion, and successfully defended her title, defeating Alison Riske in the final 6–3, 3–6, 6–1.
Caroline Wozniacki was the defending champion, but lost to Naomi Osaka in the semifinals.
Julia Görges was the two-time defending champion, but lost in the quarterfinals to Caroline Wozniacki.
Misaki Doi was the defending champion but chose not to participate.
Victoria Azarenka was the defending champion, but lost in the third round to eventual champion Ashleigh Barty.
Anna Chakvetadze was the champion when the event was last held in 2010, but she retired from professional tennis in 2013.
Aryna Sabalenka was the defending champion, but she chose not to compete this year.
This was the first edition of the women's event.