After seven years with the Bianconeri, Bonucci is set to leave Milan to join their Serie A rivals for a €42 million fee, reaching a reported five-year deal with Vincenzo Montella's side.
The 30-year-old defender arrived in Milan earlier in the day, and the move will become official pending a medical.
The Rossoneri initially offered €30m for the 30-year-old, but Juve refused to accept less than €40m for a centre-back who played a key role in their Serie A and Coppa Italia success and journey to the Champions League final last season.
During the campaign, the relationship between Bonucci and coach Massimiliano Allegri went sour when they had a row on the touchline during a game against Palermo in February. Allegri then left him out of the squad for the following match against Porto in the Champions League.
As reports of further arguments between the two emerged, it has been said the coach did not want Bonucci back at the Bianconeri for 2017-18.
After joining Inter as a youngster and making a few appearances for the first-team, Bonucci moved to Bari before Juve. He played over 300 games and won six Serie A titles, three Coppas Italia and three Supercoppas Italiana with the Turin club.
Prior to Bonucci's potential arrival, Milan had already spent over €100m on players in the transfer window, including Andre Silva, Ricardo Rodriguez and Franck Kessie.