See main article: article and 2023 Croatia Open Umag.
Alexei Popyrin defeated Stan Wawrinka in the final, 6–7(5–7), 6–3, 6–4 to win the singles tennis title at the 2023 Croatia Open Umag.[1] It was his second ATP Tour singles title.
Jannik Sinner was the reigning champion,[2] but chose not to defend his title.
The top four seeds received a bye into the second round.