[citation needed] In August 2019, he joined Inter Milan for an estimated fee of €750,000.

[citation needed] He went on to feature on the bench for several Serie A and UEFA Champions League matches.

[9] On 27 August 2024, Fontanarosa joined Serie B club Reggiana on a season-long loan.

[10] On 3 February 2025, Fontanrosa joined fellow Serie B side Carrarese on loan for the remainder of the season.

[12] In May 2023, he was included by head coach Carmine Nunziata in the Italian squad that took part in the FIFA U-20 World Cup in Argentina,[13] where the Azzurrini finished runners-up after losing to Uruguay in the final match.