2020 St. Petersburg Open – Singles

The tournament was played on a hard surface. Due to the ongoing COVID-19 pandemic and many ATP tournaments having been cancelled, this year's event was upgraded to ATP 500 level.

Daniil Medvedev was the defending champion, but lost in the second round to Reilly Opelka.

Andrey Rublev won the title, defeating last year finalist Borna Ćorić in the final, 7–6(7–5), 6–4.

Seeds
• # 🇷🇺 Daniil Medvedev (second round)

• # 🇨🇦 Denis Shapovalov (semifinals)

• # 🇷🇺 Andrey Rublev (champion)

• # 🇷🇺 Karen Khachanov (quarterfinals)

• # Stan Wawrinka (quarterfinals)

• # 🇨🇦 Milos Raonic (semifinals)

• # Borna Ćorić (final)

• # 🇺🇸 Taylor Fritz (first round)

Seeds
• # 🇺🇸 J. J. Wolf (qualified)

• # 🇧🇾 Ilya Ivashka (qualified)

• # 🇷🇸 Nikola Milojević (qualifying competition)

• # 🇪🇨 Emilio Gómez (qualifying competition, lucky loser)

• # Ernests Gulbis (first round)

• # 🇦🇹 Jurij Rodionov (first round)

• # 🇷🇸 Viktor Troicki (qualifying competition, lucky loser)

• # 🇹🇷 Cem İlkel (first round)

Qualifiers
• # 🇺🇸 J. J. Wolf

• # 🇧🇾 Ilya Ivashka

• # Nino Serdarušić

• # 🇷🇺 Pavel Kotov

Lucky losers
• # 🇪🇨 Emilio Gómez

• # 🇷🇸 Viktor Troicki