The 2025 Zagreb Open was a professional tennis tournament played on outdoor clay courts. It was part of the 2025 ATP Challenger Tour and the 2025 ITF Women's World Tennis Tour. It took place in Zagreb, Croatia between 12 and 17 May 2025.
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 players received entry into the singles main draw as alternates:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
The following players received wildcards into the singles main draw:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser: