135, Marozsán made his ATP and Masters 1000 debut at the 2023 Italian Open after qualifying into the main draw.

[8] He made his debut at the 2023 Wimbledon Championships as a lucky loser after the late withdrawal of Nick Kyrgios.

[11] He became the first Hungarian to reach a quarterfinal at the Masters 1000 level since the series began in 1990 with a top-10 win over Casper Ruud.

[13] He reached another quarterfinal at the 2023 Sofia Open defeating Roberto Bautista Agut coming back from a break down in the third set and converting his fourth match point, before losing to Jan-Lennard Struff.

[15] At the 2024 BNP Paribas Open he reached the fourth round of a Masters for the third time in his career defeating lucky loser Jurij Rodionov, 24th seed Nicolás Jarry and qualifier Thiago Seyboth Wild.

At the 2024 Miami Open he reached again the fourth round of a Masters, this time defeating Aleksandar Kovacevic, upsetting sixth seed Holger Rune, for his third top-10 win, dropping only two games en route in less than one hour,[16][17] and Alexei Popyrin also in straight sets.

[19] At the 2025 Australian Open Marozsan reached again the third round defeating 17th seed Frances Tiafoe, in his second fifth setter at the tournament.