The 2025 Kozerki Open was a professional tennis tournament played on hard courts. It was the fourth edition of the tournament which was part of the 2025 ATP Challenger Tour. It took place in Grodzisk Mazowiecki, Poland between 4 and 10 August 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 player received entry into the singles main draw as a special exempt:
The following player received entry into the singles main draw through the Next Gen Accelerator programme:
The following players received entry into the singles main draw as alternates:
The following players received entry from the qualifying draw: