2021 Saint Petersburg Challenger II – Singles

Zizou Bergs was the defending champion but lost in the second round to Kacper Żuk.

Evgenii Tiurnev won the title after defeating Żuk 6–4, 6–2 in the final.

Seeds
• # 🇷🇺 Roman Safiullin (first round)

• # 🇰🇿 Dmitry Popko (quarterfinals)

• # 🇹🇷 Cem İlkel (first round)

• # 🇷🇴 Marius Copil (semifinals)

• # 🇩🇪 Rudolf Molleker (second round)

• # 🇵🇱 Kacper Żuk (final)

• # 🇺🇸 Christopher Eubanks (quarterfinals)

• # 🇷🇺 Teymuraz Gabashvili (first round)