2018 Western & Southern Open – Women's singles

Kiki Bertens defeated Simona Halep in the final, 2–6, 7–6(8–6), 6–2 to win the women's singles tennis title at the 2018 Cincinnati Masters. She saved a championship point en route to her first hard court and Premier 5-level title, and defeated the world No. 2 and No. 1 players, in the second round and final, respectively. Bertens became the first Dutchwoman to win the title.

Garbiñe Muguruza was the defending champion, but lost in the second round to Lesia Tsurenko.

Seeds
The top eight seeds received a bye into the second round. • 🇷🇴 Simona Halep (final)

• Caroline Wozniacki (second round, retired)

• 🇺🇸 Sloane Stephens (third round)

• 🇩🇪 Angelique Kerber (third round)

• 🇺🇦 Elina Svitolina (quarterfinals)

• 🇫🇷 Caroline Garcia (third round)

• 🇪🇸 Garbiñe Muguruza (second round)

• 🇨🇿 Petra Kvitová (semifinals)

• 🇨🇿 Karolína Plíšková (second round)

• 🇩🇪 Julia Görges (first round, retired)

• Jeļena Ostapenko (first round)

• 🇷🇺 Daria Kasatkina (first round)

• 🇺🇸 Madison Keys (quarterfinals)

• 🇺🇸 Venus Williams (withdrew)

• 🇧🇪 Elise Mertens (quarterfinals)

• 🇦🇺 Ashleigh Barty (third round)

• 🇯🇵 Naomi Osaka (first round)

Seeds
• # 🇫🇷 Alizé Cornet (qualified)

• # 🇧🇾 Aliaksandra Sasnovich (qualified)

• # Donna Vekić (qualifying competition)

• # 🇮🇹 Camila Giorgi (qualifying competition, lucky loser)

• # 🇧🇪 Alison Van Uytvanck (first round, retired)

• # Hsieh Su-wei (first round)

• # Belinda Bencic (first round)

• # 🇧🇪 Kirsten Flipkens (first round)

• # 🇪🇪 Kaia Kanepi (qualified)

• # 🇰🇿 Yulia Putintseva (qualifying competition)

• # Petra Martić (qualified)

• # 🇷🇴 Sorana Cîrstea (qualifying competition)

• # 🇸🇰 Viktória Kužmová (qualified)

• # 🇦🇺 Ajla Tomljanović (qualified)

• # 🇵🇱 Magda Linette (first round)

• # 🇰🇿 Zarina Diyas (qualifying competition)

• # 🇦🇺 Samantha Stosur (first round)

• # 🇧🇾 Vera Lapko (qualifying competition)

• # 🇺🇸 Jennifer Brady (qualifying competition)

• # 🇺🇸 Sofia Kenin (qualifying competition)

• # 🇷🇴 Monica Niculescu (first round)

• # Monica Puig (first round)

• # 🇸🇪 Rebecca Peterson (qualified)

• # 🇺🇸 Sachia Vickery (first round)

Qualifiers
• # 🇫🇷 Alizé Cornet

• # 🇧🇾 Aliaksandra Sasnovich

• # 🇷🇴 Ana Bogdan

• # 🇸🇰 Viktória Kužmová

• # Stefanie Vögele

• # 🇩🇪 Tatjana Maria

• # 🇺🇸 Varvara Lepchenko

• # 🇺🇸 Allie Kiick

• # 🇪🇪 Kaia Kanepi

• # 🇸🇪 Rebecca Peterson

• # Petra Martić

• # 🇦🇺 Ajla Tomljanović

Lucky loser
• # 🇮🇹 Camila Giorgi