2021 St. Petersburg Open

The 2021 St. Petersburg Open was a tennis tournament played on indoor hard courts. It was the 26th edition of the St. Petersburg Open, and part of the ATP World Tour 250 Series of the 2021 ATP Tour. It took place at the Sibur Arena in Saint Petersburg, Russia, from October 25 through 31, 2021.

Singles
Marin Čilić def. 🇺🇸 Taylor Fritz, 7–6(7–3), 4–6, 6–4

Doubles
🇬🇧 Jamie Murray / 🇧🇷 Bruno Soares def. 🇰🇿 Andrey Golubev / Hugo Nys, 6–3, 6–4

Seeds

 * Rankings are as of 18 October 2021

Other entrants
The following players received wildcards into the singles main draw:
 * 🇮🇱 Yshai Oliel
 * Nino Serdarušić
 * 🇷🇺 Evgenii Tiurnev

The following player received entry using a protected ranking:
 * 🇪🇸 Pablo Andújar

The following players received entry from the qualifying draw:
 * 🇧🇾 Egor Gerasimov
 * 🇯🇵 Yoshihito Nishioka
 * 🇫🇮 Emil Ruusuvuori
 * Botic van de Zandschulp

Seeds

 * Rankings are as of October 18, 2021

Other entrants
The following pairs received wildcards into the doubles main draw:
 * 🇮🇱 Jonathan Erlich / 🇧🇾 Andrei Vasilevski
 * 🇷🇺 Daniil Golubev / 🇷🇺 Evgenii Tiurnev