| Date: | 6–12 December |
| Edition: | 3rd |
| Surface: | Clay |
| Location: | Maia, Portugal |
| Champs: |  Geoffrey Blancaneaux |
| Champd: | Nuno Borges / Francisco Cabral |
| After Year: | 2021 |
| After Name: | Maia Challenger II |
The 2021 Maia Challenger was a professional tennis tournament played on clay courts. It was the third edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Maia, Portugal from 6 to 12 December 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Slovakia | Andrej Martin | 121 | 1 | |
 Belgium | Kimmer Coppejans | 205 | 2 | |
| Gastão Elias | 222 | 3 | ||
| João Domingues | 248 | 4 | ||
| Nuno Borges | 253 | 5 | ||
| Tseng Chun-hsin | 254 | 6 | ||
 Canada | Steven Diez | 269 | 7 | |
| France | Geoffrey Blancaneaux | 281 | 8 |
The following players received wildcards into the singles main draw:
The following players received entry into the singles main draw using protected rankings:
The following players received entry from the qualifying draw:
Lorenzo Bocchi
Miguel Damas Simone RoncalliSee main article: 2021 Maia Challenger – Singles.
Geoffrey Blancaneaux def. Tseng Chun-hsin 3–6, 6–3, 6–2.See main article: 2021 Maia Challenger – Doubles.
Andrej Martin / Gonçalo Oliveira 6–3, 6–4.