The 2023 Sibiu Open was a professional tennis tournament played on clay courts. It was the 12th edition of the tournament which was part of the 2023 ATP Challenger Tour. It took place in Sibiu, Romania between 18 and 24 September 2023.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Hungary | Zsombor Piros | 111 | 1 | |
 Italy | Flavio Cobolli | 132 | 2 | |
 Bosnia and Herzegovina | Damir Džumhur | 157 | 3 | |
| Ivan Gakhov | 161 | 4 | ||
| Italy | Stefano Travaglia | 205 | 5 | |
| Duje Ajduković | 206 | 6 | ||
| Italy | Alessandro Giannessi | 214 | 7 | |
| Bosnia and Herzegovina | Nerman Fatić | 218 | 8 |
The following players received wildcards into the singles main draw:
Cezar Crețu Sebastian GimaThe following players received entry from the qualifying draw:
Vlad Andrei Dancu
Calvin Hemery Filip Cristian Jianu
Andrew Paulson Michael VrbenskýSee main article: 2023 Sibiu Open – Singles.
Nerman Fatić def. Damir Džumhur 6–2, 6–4.See main article: 2023 Sibiu Open – Doubles.
Andrew Paulson / Michael Vrbenský def. 
Piotr Matuszewski / Kai Wehnelt 6–2, 6–2.