The 2021 Cassis Open Provence was a professional tennis tournament played on hard courts. It was the 3rd edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Cassis, France between 6 and 12 September 2021.
Singles main-draw entrants
Seeds
1 Rankings are as of 30 August 2021.
Other entrants
The following players received wildcards into the singles main draw: Clément Chidekh Arthur Fils Luca Van Assche
The following players received entry into the singles main draw as alternates: Hugo Grenier Tatsuma Ito Bernard Tomic Yosuke Watanuki
The following players received entry from the qualifying draw: Nicolás Jarry Hiroki Moriya Giovanni Mpetshi Perricard Ramkumar Ramanathan
The following players received entry as lucky losers: Arthur Cazaux Alexis Galarneau Laurent Lokoli
Champions
Singles
Benjamin Bonzi def. Lucas Pouille 7–6(7–4), 6–4.
Doubles
Sriram Balaji / Ramkumar Ramanathan def. Hans Hach Verdugo / Miguel Ángel Reyes-Varela 6–4, 3–6, [10–6].