Petra Kvitová defeated Garbiñe Muguruza in the final, 6–2, 6–1 to win the singles tennis title at the 2021 WTA Qatar Open. The final was a rematch of the 2018 final. It was Kvitová's second title at the WTA Qatar Open. Kvitová dropped just one set the entire tournament, to Anett Kontaveit in the quarterfinals.
Aryna Sabalenka was the defending champion, but lost in the second round to Muguruza.
Seeds The top four seeds received a bye into the second round.
Draw
Finals
Top half
Bottom half
Qualifying
Seeds
Qualifiers
Lucky loser Misaki Doi
Draw
First qualifier
Second qualifier
Third qualifier
Fourth qualifier
Notes
References Main draw Qualifying draw