| 2021 Tennis Napoli Cup | |
|---|---|
| Date | 4–10 October |
| Edition | 20th |
| Surface | Clay |
| Location | Naples, Italy |
| Champions | |
| Singles | |
 Tallon Griekspoor | |
| Doubles | |
 Dustin Brown /  Andrea Vavassori | |
The 2021 Tennis Napoli Cup was a professional tennis tournament played on clay courts. It was the 20th edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Naples, Italy between 4 and 10 October 2021.
| Country | Player | Rank1 | Seed |
|---|---|---|---|
| ITA | Stefano Travaglia | 97 | 1 |
 SVK | Andrej Martin | 122 | 2 |
| GER | Yannick Hanfmann | 123 | 3 |
| NED | Tallon Griekspoor | 131 | 4 |
 CZE | Zdeněk Kolář | 148 | 5 |
| ITA | Alessandro Giannessi | 181 | 6 |
| ITA | Gian Marco Moroni | 205 | 7 |
| ITA | Lorenzo Giustino | 213 | 8 |
The following players received wildcards into the singles main draw:
The following player received entry into the singles main draw using a protected ranking:
The following player received entry into the singles main draw as an alternate:
The following players received entry from the qualifying draw:
Bogdan Ionuț Apostol Raúl Brancaccio Marco Miceli Julian Ocleppo The following players received entry as lucky losers:
Tallon Griekspoor def. Andrea Pellegrino 6–3, 6–2. Dustin Brown / Andrea Vavassori def. 
Mirza Bašić / 
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