He made his professional and Serie A debut in a 4–0 win over Frosinone on 26 September 2018, making the assist for Aleksandar Kolarov's goal.

[5][6] He made his UEFA Champions League debut on 2 October 2018, in the group stage match won 5–0 against FC Viktoria Plzeň.

[12] On 17 August 2023, Pellegrini rejoined Lazio on a two-year loan with the option to make the deal permanent, which becomes an obligation if certain conditions are met.

[14] He received his first call up to the Italy senior squad for the team's UEFA Euro 2020 qualifying matches against Armenia and Finland in September 2019.

[15] He made his senior debut with Italy on 11 November 2020, featuring as a substitute in a 4–0 friendly win over Estonia in Florence.