During his time at Brighton, Estupinan made 104 appearances and scored five goals.
Brighton's manager, Fabian Hurzeler, expressed his gratitude towards Estupinan, saying, "I have enjoyed working with Pervis and he has made a significant contribution to the club during his time here."
Hurzeler also acknowledged Estupinan's desire for a new challenge, stating, "He is at the stage of his career when he wants a fresh challenge, and this opportunity to play in Serie A gives him that."
The transfer fee involved in the deal has not been disclosed by either Brighton or Milan.
