Following a quarterfinal berth on his debut in a Challenger main draw in
Lugano as a wildcard, Brunold reached the top 750 after a rise of more than 150 positions to world No. 725 on 20 March 2023. Brunold made his ATP main draw doubles debut at the
2023 Swiss Open Gstaad after receiving a wildcard into the doubles main draw with
Kilian Feldbausch. He also received a wildcard for the qualifying competition of the
2023 Swiss Indoors in singles and for the main draw in doubles with
Marc-Andrea Hüsler. He received a wildcard for the
2024 Swiss Indoors qualifying competition, where he lost to
James Duckworth. He received a wildcard for the
2025 Swiss Indoors qualifying competition, but lost to
Reilly Opelka, unable to capitalize on six match points. ==Personal life==