[4] Andrei Coubiș entered the Primavera squad of AC Milan in 2021,[5] a side he eventually captained.
[6] He also then made headlines in the Youth League, as he scored against RB Salzburg for the opening game of the Milanisti.
[7][8] On the summer of 2024, he was assigned to the newly created reserve team Milan Futuro, set to compete in the Serie C Group B.
[9] Coubiș made his professional debut with Milan Futuro on 17 August 2024, coming on as a substitute for Álex Jiménez at the 74th minute of a 2–1 away win Coppa Italia Serie C round of 16 match against Novara.
[11] He scored his first professional goal with Milan Futuro on 23 February 2025, for a 3–2 home loss Serie C match against Pescara.