The Rossoneri have picked up the former Cagliari keeper on a free transfer after his contract at Chievo came to an end.
The 29-year-old's brief stay at the Marc'Antonio Bentegodi ended at the end of the season and the San Siro outfit has pounced, signing him on a free transfer.
"AC Milan announce the they have signed Michael Agazzi, who has signed a contract expiring on June 30, 2017," a club statement read.
Agazzi began his professional career at South Tyrol and made over 100 league appearances for Cagliari but is likely to play backup to Christian Abbiati, who extended his contract earlier this week.
The current second-choice keeper, Marco Amelia, is likely to leave the club this summer.