Vavassori is a mixed doubles Grand Slam champion with Sara Errani, lifting the title at the 2024 US Open on their team debut at the event.

At the 2023 Grand Prix Hassan II he reached his first ATP singles quarterfinal as a qualifier defeating eight seed Nicolás Jarry and Jaume Munar.

37 and 31st seed Miomir Kecmanović in 5 hours and 10 minutes, the second longest match of the season after Kokkinakis against Murray at the Australian Open, for his first Grand Slam win.

[12] He qualified for the Argentina Open defeating Thiago Seyboth Wild and seventh seed Laslo Djere to reach his second ATP singles quarterfinal.

[18] At the Miami Open he also reached the singles main draw after qualifying, making his debut at this Masters and recorded his first round win over Pedro Cachin but lost to second seed and eventual champion Jannik Sinner.

156, he entered the main draw at the Barcelona Open as a lucky loser directly into the second round replacing seventh seed Karen Khachanov after his late withdrawal.

[21] Partnering Sara Errani, he won the mixed doubles title at the US Open, defeating Taylor Townsend and Donald Young in the final.

[22][23] Vavassori and Bolelli won the China Open in October, defeating third seeds Harri Heliövaara and Henry Patten in the final.

[27] The pair reached the final at the Australian Open, losing to sixth seeds Harri Heliövaara and Henry Patten.

316, he qualified for the singles main draw of the ATP 500 2025 ABN AMRO Open where he upset former Rotterdam champion Felix Auger-Aliassime following his retirement from the match.