In 2016, at the age of 15 years and 280 days, Pellegri joined Amedeo Amadei as the joint-youngest player to appear in Serie A at the time.
[3] On 17 September 2017, he became the first 16-year-old to score twice in a single major European league game in a 3–2 home loss to Lazio;[8][9] his brace also made him the youngest player ever in Serie A to have managed to do so.
[12] He made his Monaco debut on 16 February in a 4–0 home win against Dijon in Ligue 1, coming on for the final four minutes in place of Keita Baldé.
[15] On 25 August 2021, AC Milan announced the signing of Pellegri from Monaco on a temporary loan basis, with the option to make the deal permanent, which becomes an obligation if certain conditions are met.
[12] Pellegri made his senior debut for Italy on 11 November 2020, aged 19, featuring as a substitute in a friendly match won 4–0 against Estonia in Florence.