2021 BMW Open – Singles

Nikoloz Basilashvili defeated Jan-Lennard Struff in the final, 6–4, 7–6(7–5) to win the men's singles tennis title at the 2021 Bavarian International Tennis Championships. After not dropping a set en route to his victory, Basilashvili earned his second title of the season and his fifth career ATP Tour singles title overall. Struff was in contention to win his first title in his first tour-level final.

Cristian Garín was the defending champion from when the tournament was last held in 2019, but he competed at the simultaneous Estoril Open instead.

Seeds
The top four seeds received a bye into the second round. • #🇩🇪 Alexander Zverev (quarterfinals)

• #🇳🇴 Casper Ruud (semifinals)

• #🇷🇺 Aslan Karatsev (withdrew)

• #🇷🇸 Filip Krajinović (quarterfinals)

• # Nikoloz Basilashvili (champion)

• #🇷🇸 Dušan Lajović (first round)

• #🇩🇪 Jan-Lennard Struff (final)

• #🇦🇺 John Millman (quarterfinals)

Seeds
• # Ričardas Berankis (qualifying competition, lucky loser)

• # 🇸🇰 Norbert Gombos (qualifying competition, lucky loser)

• # 🇸🇰 Andrej Martin (qualifying competition, lucky loser)

• # 🇯🇵 Yūichi Sugita (first round)

• # 🇦🇹 Dennis Novak (qualifying competition)

• # 🇧🇾 Ilya Ivashka (qualified)

• # 🇨🇴 Daniel Elahi Galán (qualified)

• # 🇺🇸 Mackenzie McDonald (qualified)

Qualifiers
• # 🇧🇾 Ilya Ivashka

• # 🇨🇴 Daniel Elahi Galán

• # 🇺🇸 Mackenzie McDonald

• # 🇩🇪 Cedrik-Marcel Stebe

Lucky losers
• # 🇱🇹 Ričardas Berankis

• # 🇸🇰 Norbert Gombos

• # 🇸🇰 Andrej Martin