*Club domestic league appearances and goals, correct as of 23:01, 30 August 2024 (UTC) ‡ National team caps and goals, correct as of 23:47, 9 September 2024 (UTC)
On 22 October 2019, he made his UEFA Champions League debut against Paris Saint-Germain. He started the game and was substituted in the 57th minute with the score of 1–0 to Paris Saint-Germain, the game eventually ended with a 5–0 loss.[5] On 5 February 2020, he scored a goal in a 2–1 win against Zulte Waregem to reach the Belgian Cup final.[6]
On 2 August 2022, De Ketelaere joined Serie A club AC Milan on a contract until 30 June 2027.[8] Signed for a fee reported to be in the range of €35 million, De Ketelaere however failed to fulfill the initial expectations of the Rossoneri, scoring no goals throughout the entire season and making only nine league starts.[9]
Loan to Atalanta
On 16 August 2023, Atalanta formally confirmed the signing of De Ketelaere from AC Milan on a loan move with an option to buy.[10] On 20 August 2023, De Ketelaere came off the bench during Atalanta's Serie A match against Sassuolo, striking the crossbar before sealing his debut Serie A goal with a precise header.[11] The match ended 2–0 in Atalanta's favor.[12] On 21 September, De Ketelaere marked his presence by netting his first goal in a UEFA Europa Leaguegroup stage match against Raków Częstochowa, contributing to Atalanta's 2–0 victory.[13][14] De Ketelaere scored 14 goals and provided 11 assists in all competitions during his first season at Atalanta; the club made his move permanent on 15 June 2024.[15]