See main article: 2021 Brest Challenger.
Denys Molchanov and Andrei Vasilevski were the defending champions[1] but only Molchanov chose to defend his title, partnering Aleksandr Nedovyesov. Molchanov lost in the semifinals to Sadio Doumbia and Fabien Reboul.
Doumbia and Reboul won the title after defeating Salvatore Caruso and Federico Gaio 4–6, 6–3, [10–3].