The 2023 Oeiras Indoors II was a professional tennis tournament played on hard courts. It was the 2nd edition of the tournament which was part of the 2023 ATP Challenger Tour. It took place in Oeiras, Portugal from 9 to 14 January 2023.
The following players received wildcards into the singles main draw:
The following player received entry into the singles main draw as a special exempt:
The following players received entry from the qualifying draw:
