2021 Australian Open – Women's singles

Naomi Osaka defeated Jennifer Brady in the final, 6–4, 6–3 to win the women's singles tennis title at the 2021 Australian Open. It was her second Australian Open title and fourth major title overall. With the win, Osaka extended her winning streak to 21 matches, dating to the 2020 Cincinnati Open. She only lost one set during the tournament, to Garbiñe Muguruza in the fourth round; she also saved two match points in that match, making her the eighth woman to win the Australian Open after saving match points. Osaka became the third player in the Open Era, after Monica Seles and Roger Federer, to win their first four major finals.

Sofia Kenin was the defending champion, but lost to Kaia Kanepi in the second round.

Venus Williams became the first player to win a match at a major after turning 40 since Martina Navratilova at the 2004 Wimbledon Championships.

Mayar Sherif became the first Egyptian woman to win a major main draw match. Hsieh Su-wei became the first Taiwanese woman to make a major singles quarterfinal. At 35 years of age, Hsieh also became the oldest player to make her quarterfinal debut.

Serena Williams equaled Chris Evert's all-time record of 54 major quarterfinals at this tournament; she then lost to Osaka in the semifinals. This was the seven-time champion's final appearance at the event, as Williams announced her retirement from professional tennis the following year.

Seeds
Seeding per WTA rankings. • 🇦🇺 Ashleigh Barty (quarterfinals)

• 🇷🇴 Simona Halep (quarterfinals)

• 🇯🇵 Naomi Osaka (champion)

• 🇺🇸 Sofia Kenin (second round)

• 🇺🇦 Elina Svitolina (fourth round)

• 🇨🇿 Karolína Plíšková (third round)

• 🇧🇾 Aryna Sabalenka (fourth round)

• 🇨🇦 Bianca Andreescu (second round)

• 🇨🇿 Petra Kvitová (second round)

• 🇺🇸 Serena Williams (semifinals)

• Belinda Bencic (third round)

• 🇧🇾 Victoria Azarenka (first round)

• 🇬🇧 Johanna Konta (first round, retired)

• 🇪🇸 Garbiñe Muguruza (fourth round)

• 🇵🇱 Iga Świątek (fourth round)

•  Petra Martić (first round)

• 🇰🇿 Elena Rybakina (second round)

• 🇧🇪 Elise Mertens (fourth round)

• 🇨🇿 Markéta Vondroušová (fourth round)

•  Maria Sakkari (first round)

• 🇪🇪 Anett Kontaveit (third round)

• 🇺🇸 Jennifer Brady (final)

• 🇩🇪 Angelique Kerber (first round)

• 🇺🇸 Alison Riske (first round)

• 🇨🇿 Karolína Muchová (semifinals)

• 🇰🇿 Yulia Putintseva (third round)

• 🇹🇳 Ons Jabeur (third round)

•  Donna Vekić (fourth round)

• 🇷🇺 Ekaterina Alexandrova (third round)

• 🇨🇳 Wang Qiang (first round)

• 🇨🇳 Zhang Shuai (first round)

• 🇷🇺 Veronika Kudermetova (third round)

Wild cards
• 🇦🇺 Destanee Aiava

• 🇦🇺 Kimberly Birrell

• 🇦🇺 Lizette Cabrera

• 🇦🇺 Daria Gavrilova

• 🇦🇺 Maddison Inglis

• 🇦🇺 Arina Rodionova

• 🇦🇺 Astra Sharma

• 🇦🇺 Samantha Stosur

Protected ranking
• 🇩🇪 Mona Barthel (101)

• 🇬🇧 Katie Boulter (85)

• 🇰🇿 Yaroslava Shvedova (47)

• 🇷🇺 Vera Zvonareva (78)

Qualifiers
• 🇭🇺 Tímea Babos

• 🇫🇷 Clara Burel

• 🇮🇹 Elisabetta Cocciaretto

• 🇷🇸 Olga Danilović

• 🇮🇹 Sara Errani

• 🇯🇵 Mayo Hibi

• 🇬🇧 Francesca Jones

• Kaja Juvan

• 🇨🇦 Rebecca Marino

• 🇧🇪 Greet Minnen

• 🇺🇸 Whitney Osuigwe

• 🇫🇷 Chloé Paquet

• 🇧🇬 Tsvetana Pironkova

• 🇷🇺 Liudmila Samsonova

• 🇷🇺 Valeria Savinykh

• 🇪🇬 Mayar Sherif

Lucky losers
• 🇧🇪 Ysaline Bonaventure

• 🇷🇴 Mihaela Buzărnescu

• 🇷🇺 Margarita Gasparyan

• 🇸🇰 Anna Karolína Schmiedlová

Potential lucky losers
• # 🇺🇦 Lesia Tsurenko (did not play)

• # 🇷🇺 Kamilla Rakhimova (did not play)

• # 🇺🇸 Varvara Lepchenko (did not play)

• # 🇮🇳 Ankita Raina (did not play)

Withdrawals
• † 🇪🇸 Carla Suárez Navarro (83) → replaced by 🇩🇪 Mona Barthel (101 PR)

• † 🇺🇸 Taylor Townsend (89) → replaced by 🇩🇪 Andrea Petkovic (102)

• & Kiki Bertens (9) → replaced by 🇪🇸 Aliona Bolsova (103)

• & 🇺🇸 Amanda Anisimova (30) → replaced by 🇧🇪 Ysaline Bonaventure (LL)

• & 🇵🇱 Magda Linette (40) → replaced by 🇷🇺 Margarita Gasparyan (LL)

• & 🇺🇸 Madison Keys (16) → replaced by 🇸🇰 Anna Karolína Schmiedlová (LL)

• & 🇺🇦 Dayana Yastremska (suspension by ITF, upheld by CAS) (29) → replaced by 🇷🇴 Mihaela Buzărnescu (LL)

† – not included on entry list & – withdrew from entry list