Tonali had been heavily linked with a move to Inter until Antonio Conte’s side sought to prioritise other options, allowing the Rossoneri to step in as favourites for his signature in recent weeks.
“The player will wear the number 8 jersey.”
Both Ivan Gazidis and Paolo Maldini expressed their delight with the signing upon its completion.
“We are excited to welcome Sandro to the Rossoneri family,” Maldini said.
“As a talented, young midfielder he will not only embrace the values of AC Milan but also make a significant contribution to the future success of the club.”