2025 BOSS Open – Singles
| Singles | |
|---|---|
| 2025 BOSS Open | |
| Champion | Taylor Fritz |
| Runner-up | Alexander Zverev |
| Score | 6–3, 7–6(7–0) |
| Draw | 28 (4 Q / 3 WC ) |
| Seeds | 8 |
Taylor Fritz defeated Alexander Zverev in the final, 6–3, 7–6(7–0) to win the singles tennis title at the 2025 Stuttgart Open. He won the title without losing a set or having his serve broken during the tournament. It was Fritz's fourth grass court title, and ninth ATP Tour singles title overall.
Jack Draper was the reigning champion, but did not participate this year.
At 17 years and eight months old, Justin Engel was the second-youngest player since 1990 to win a tour-level match (excluding Davis Cup) on three surfaces, after Rafael Nadal. He became the youngest quarterfinalist in the tournament's history and the youngest at any grass-court tournament since Boris Becker at the 1985 Wimbledon Championships.