Casper Ruud defeated Hugo Gaston in the final, 6–3, 6–2, to win the men's singles tennis title at the 2021 Swiss Open.
Albert Ramos Viñolas was the reigning champion from when the tournament was last held in 2019, but chose to compete in Umag instead.
Seeds The top four seeds receive a bye into the second round.
Draw
Finals
Top half
Bottom half
Qualifying
Seeds
Qualifiers
Lucky losers
Qualifying draw
First qualifier
Second qualifier
Third qualifier
Fourth qualifier
References
External links Main draw Qualifying draw