The 2021 Split Open II was a professional tennis tournament played on clay courts. It was part of the 2021 ATP Challenger Tour. It took place in Split, Croatia between 12 and 18 April 2021.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 France | Grégoire Barrère | 116 | 1 | |
 Australia | Marc Polmans | 149 | 2 | |
| France | Hugo Gaston | 158 | 3 | |
 Egypt | Mohamed Safwat | 160 | 4 | |
 Belgium | Kimmer Coppejans | 168 | 5 | |
 Italy | Lorenzo Giustino | 169 | 6 | |
 Slovakia | Filip Horanský | 175 | 7 | |
 Canada | Steven Diez | 177 | 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 into the singles main draw as special exempts:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
See main article: 2021 Split Open II – Singles.
Kacper Żuk def. Mathias Bourgue 6–4, 6–2.See main article: 2021 Split Open II – Doubles.
Szymon Walków / Jan Zieliński def. Grégoire Barrère / Albano Olivetti 6–2, 7–5.
