The 2021 Maia Challenger II was a professional tennis tournament played on clay courts.

It was the fourth edition of the tournament which was part of the 2021 ATP Challenger Tour.

It took place in Maia, Portugal from 13 to 19 December 2021.

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 into the singles main draw as alternates: The following players received entry from the qualifying draw: