Who was the last player to defeat Serena Williams in a Grand Slam final?

Bianca Andreescu was the last player to defeat Serena Williams in a Grand Slam final, beating her at the 2019 US Open.

Andreescu won the final in straight sets, 6–3, 7–5, capturing her first major singles title. The victory made her the first Canadian to win a major singles championship and the first player born in the 2000s to win one.

The match was especially significant for Williams, who was seeking a record-tying 24th Grand Slam singles title. She had reached four major finals after returning to competition following the birth of her daughter, but lost each one. Andreescu’s win therefore became the final Grand Slam-final defeat of Williams’s career.

A common mix-up is confusing Andreescu with Naomi Osaka, who defeated Williams in the 2018 US Open final. Osaka was Williams’s previous Grand Slam-final opponent, while Andreescu was the last.