The Rossoneri reached an agreement to land the Italy international last week and, after passing a medical and agreeing personal terms, he is now officially a Milan player.
Bonucci won six Serie A titles and three Coppas Italia across his seven years in Turin, making over 300 appearances for the club during that time, the last of which came in the Champions League final defeat to Real Madrid in May.
Milan boss Vincenzo Montella, who has spent more money than any other manager in European football this summer, believes that he has landed one of the game's top central defenders.
"He is a player with international experience," he told the club's official website. "Technically, I think that he and Sergio Ramos are the strongest central defenders in the world. Coaching him is a dream come true".