2021 Silicon Valley Classic – Singles

Zheng Saisai was the reigning champion but chose not to participate.

Danielle Collins won the title, her second consecutive singles title on the WTA Tour, defeating Daria Kasatkina in the final, 6–3, 6–7(10–12), 6–1.

Seeds
• # 🇧🇪 Elise Mertens (semifinals)

• # 🇰🇿 Elena Rybakina (quarterfinals)

• # 🇺🇸 Madison Keys (second round)

• # 🇷🇺 Daria Kasatkina (final)

• # 🇷🇺 Veronika Kudermetova (withdrew)

• # Petra Martić (second round)

• # 🇺🇸 Danielle Collins (champion)

• # 🇰🇿 Yulia Putintseva (quarterfinals)

• # 🇺🇸 Alison Riske (second round)

Seeds
• #🇷🇺 Anastasia Potapova (qualifying competition)

• #🇺🇸 Kristie Ahn (first round)

• #🇺🇸 Caty McNally (moved to main draw)

• # Ana Konjuh (qualified)

• #🇦🇺 Arina Rodionova (first round)

• # Lesley Pattinama Kerkhove (qualified)

• #🇷🇺 Valeria Savinykh (first round)

• #🇯🇵 Mayo Hibi (first round)

Qualifiers
• # Lesley Pattinama Kerkhove

• #🇰🇷 Han Na-lae

• #🇺🇸 Emina Bektas

• # Ana Konjuh