The 2021 Città di Forlì III was a professional tennis tournament played on hard courts.

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

It took place in Forlì, Italy between 6 and 12 December 2021.

The following players received wildcards into the singles main draw: The following players received entry into the singles main draw using protected rankings: The following player received entry into the singles main draw as an alternate: The following players received entry from the qualifying draw: