| Date: | 13–19 September 2021 |
| Edition: | 2nd |
| Surface: | Hard |
| Location: | Caldas da Rainha, Portugal |
| Category: | ITF Women's World Tennis Tour |
| Prize Money: | $60,000+H |
| Champs: |  Zheng Saisai |
| Champd: |  Momoko Kobori / Hiroko Kuwata |
| Before Name: | Oeste Ladies Open |
| After Name: | Caldas da Rainha Ladies Open |
| Before Year: | 2019 |
The 2021 Portugal Ladies Open was a professional women's tennis tournament played on outdoor hard courts. It was the second edition of the tournament which was part of the 2021 ITF Women's World Tennis Tour. It took place in Caldas da Rainha, Portugal between 13 and 19 September 2021.[1]
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| China | Zheng Saisai | 83 | 1 | |
| China | Wang Xinyu | 135 | 2 | |
 France | Harmony Tan | 138 | 3 | |
 Australia | Maddison Inglis | 144 | 4 | |
| Australia | Arina Rodionova | 157 | 5 | |
| Australia | Lizette Cabrera | 159 | 6 | |
 Brazil | Beatriz Haddad Maia | 174 | 7 | |
 Ukraine | Daria Snigur | 207 | 8 |
The following players received wildcards into the singles main draw:
Dalila SpiteriThe following player received entry using a junior exempt:
The following player received entry using a special exempt:
The following players received entry from the qualifying draw:
Elena Bogdan Salma Djoubri
Weronika Falkowska Olivia Gadecki Ioana Loredana Roșca
Raluca Șerban
Eden SilvaSee main article: 2021 Portugal Ladies Open – Singles.
Zheng Saisai def. Harmony Tan, 6–4, 3–6, 6–3See main article: 2021 Portugal Ladies Open – Doubles.
Momoko Kobori / Hiroko Kuwata def. Alicia Barnett / Olivia Nicholls, 7–6(7–5), 7–6(7–2)