2021 Hamburg European Open – Women's singles

Kim Clijsters was the defending champion, having won the previous edition in 2002,[1] but chose not to participate.

Elena-Gabriela Ruse won her maiden WTA Tour singles title as a qualifier, defeating Andrea Petkovic in the final, 7–6(8–6), 6–4.

[2] This tournament marked Dayana Yastremska's return to professional tennis, after her suspension for testing positive for a prohibited substance was lifted by the ITF.

[3] The top four seeds received a bye into the second round.