The Argentinian joins Milan on a four-year deal and is an excellent addition to the team ahead of their UEFA Europa League campaign.
Musacchio to join on July 1
Following the completion of his medical with Milan, Musacchio will be joining Vincenzo Montella's side on July 1, when the transfer window reopens.
The Argentinian is the first player to sign for Milan since the takeover of the club by Rossoneri Sport Investment Lux in early April as Silvio Berlusconi ended his long-lasting ownership of Milan.
There has been no mention of a transfer fee, however, it is reported to be somewhere around €18m spent by Milan for him.
Musacchio not the only player to join Milan
It is reported that Musacchio is not the only player Milan are signing early this summer, with Franck Kessie also nearing the completion of his move and will complete his medical in the coming days.
The club released an official statement on their website which said: "AC Milan announces the signing of Mateo Musacchio from Villarreal on a contract until June 30, 2021".
The additions of Kessie and Musacchio will be important for Milan as they face a long season ahead of them. Montella is looking to take this club step by step into the future and the signing of Musacchio is a step in the right direction.