2018 Sydney International – Women's singles

Johanna Konta was the defending champion, but lost in the first round to Agnieszka Radwańska in a rematch of the previous year's final.

Angelique Kerber won the title, defeating Ashleigh Barty in the final, 6–4, 6–4. Kerber won the title despite being two match points down in the second set in her first-round match against Lucie Šafářová.

Seeds
The top two seeds received a bye into the second round. • # 🇪🇸 Garbiñe Muguruza (quarterfinals, withdrew due to right leg injury)

• # 🇺🇸 Venus Williams (second round)

• # Jeļena Ostapenko (first round)

• # 🇬🇧 Johanna Konta (first round)

• # 🇫🇷 Kristina Mladenovic (first round, retired)

• # 🇺🇸 Sloane Stephens (first round)

• # 🇩🇪 Julia Görges (withdrew)

• # Anastasija Sevastova (first round)

Seeds
• # 🇷🇺 Ekaterina Makarova (moved to main draw)

• # 🇪🇪 Anett Kontaveit (first round, retired)

• # 🇪🇸 Carla Suárez Navarro (first round)

• # 🇺🇸 Lauren Davis (first round)

• # 🇩🇪 Carina Witthöft (qualifying competition, lucky loser)

• # Maria Sakkari (first round)

• # Monica Puig (qualifying competition)

• # 🇺🇸 Catherine Bellis (qualified)

Qualifiers
• # 🇺🇸 Catherine Bellis

• # 🇮🇹 Camila Giorgi

• # 🇺🇸 Kristie Ahn

• # Verónica Cepede Royg

Lucky losers
• # 🇪🇸 Lara Arruabarrena

• # 🇩🇪 Carina Witthöft