The 2021 WTA Romanian Open, known as the Winners Open due to sponsorship reasons, was a professional women's tennis tournament played on outdoor clay courts at the Winners Sports Club.

It was the 1st edition of the tournament held in the city of Cluj-Napoca and was a part of the 2021 WTA Tour.

[1][2] This was Petkovic's seventh WTA Tour singles title, and first since 2015.

This was the maiden WTA Tour title won by both Dzalamidze and Juvan.

The following players received wildcards into the main draw: The following player received entry using a protected ranking: The following players received entry from the qualifying draw: The following pairs received wildcards into the doubles main draw: The following pair received entry using a protected ranking: