The 2021 Split Open II was a professional tennis tournament played on clay courts. It was part of the 2021 ATP Challenger Tour. It took place in Split, Croatia between 12 and 18 April 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 players received entry into the singles main draw as special exempts:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser: