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 saved two match points en route to the title, in the fourth round against Garbiñe Muguruza. 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.