Naomi Osaka defeated Serena Williams in the final, 6–2, 6–4 to win the women's singles tennis title at the 2018 US Open.

Williams was attempting to equal Margaret Court's all-time record of 24 major singles titles, and to set a new Open Era record by winning a seventh US Open singles title.

Sloane Stephens was the defending champion, but lost to Anastasija Sevastova in the quarterfinals.

Simona Halep's first-round loss to Kaia Kanepi marked the first time in the Open Era that the top seed lost in the first round.

2 and 2015 WTA Finals champion Agnieszka Radwańska, who lost in the first round to Tatjana Maria.