The defender made a loan move to Chievo in January after struggling to make an impact at the San Siro.
The 24-year-old revealed that he had "difficulties" in his time at Milan and was glad to leave the club.
"I am very happy at Chievo and leaving Milan was a weight off my shoulders," said Acerbi.
"The Rossoneri are a great club, but I had many difficulties. I am more relaxed now, as at Milan I could not give what I wanted to."
Acerbi received his first call-up for the Italy national side last August.