The 2021 Platzmann-Sauerland Open was a professional tennis tournament played on clay courts.

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

It took place in Lüdenscheid, Germany, between 16 and 22 August 2021.

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: