| Date: | 12–18 April 2021 |
| Edition: | 1st |
| Surface: | Clay |
| Location: | Oeiras, Portugal |
| Category: | ITF Women's World Tennis Tour |
| Prize Money: | $60,000 |
| Champs: | Polona Hercog |
| Champd: |  Lidziya Marozava /  Andreea Mitu |
The 2021 Oeiras Ladies Open was a professional women's tennis tournament played on outdoor clay courts. It was the first edition of the tournament which was part of the 2021 ITF Women's World Tennis Tour. It took place in Oeiras, Portugal between 12 and 18 April 2021.[1]
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| Polona Hercog | 60 | 1 | ||
 Belgium | Greet Minnen | 117 | 2 | |
 Ukraine | Anhelina Kalinina | 161 | 3 | |
 Turkey | ||||
 France | Clara Burel | 175 | 5 | |
 Luxembourg | Mandy Minella | 184 | 6 | |
| France | Chloé Paquet | 186 | 7 | |
 Spain | Georgina García Pérez | 194 | 8 | |
 Georgia | Mariam Bolkvadze | 195 | 9 | |
 Slovakia | Rebecca Šramková | 196 | 10 | |
| Ukraine | Daria Snigur | 197 | 11 | |
 Serbia | Natalija Kostić | 199 | 12 | |
 United Kingdom | Francesca Jones | 200 | 13 | |
 Italy | Martina Di Giuseppe | 201 | 14 | |
 Russian Federation | Marina Melnikova | 203 | 15 | |
 China | Lu Jiajing | 210 | 16 |
The following players received wildcards into the singles main draw:
Beatriz Haddad Maia Elizabet HamaliyThe following player received entry using a protected ranking:
The following player received entry using a junior exempt:
The following player received entry using as a special exempt:
The following players received entry from the qualifying draw:
Federica Di Sarra
Jang Su-jeong Diane Parry Olga Sáez Larra
Katie VolynetsThe following player received entry as a lucky loser:
See main article: 2021 Oeiras Ladies Open – Singles.
Clara Burel, walkoverSee main article: 2021 Oeiras Ladies Open – Doubles.
Lidziya Marozava / Andreea Mitu def. Marina Melnikova / Conny Perrin, 3–6, 6–4, [10–3]