The 2021 Zagreb Ladies Open was a professional women's tennis tournament played on outdoor clay courts.

It was the tenth edition of the tournament which was part of the 2021 ITF Women's World Tennis Tour.

It took place in Zagreb, Croatia between 26 April and 2 May 2021.

[1] The following players received wildcards into the singles main draw: The following players received entry using protected rankings: The following player received entry using a junior exempt: The following players received entry from the qualifying draw: The following players received entry as a lucky losers: