Alessio Romagnoli was welcomed to Milan by chief Adriano Galliani after sealing his move to San Siro.
Milan have completed the signing of defender Alessio Romagnoli from Roma on a five-year deal for an undisclosed fee.
Reports of a switch for the Italy under-21 centre-back gathered pace over the weekend before chief executive Adriano Galliani confirming the deal was all but done on Sunday.
Romagnoli passed his medical on Tuesday and will now be reunited with coach Sinisa Mihajlovic, who signed the 20-year-old on loan while in charge of Sampdoria last season.
"Welcome Alessio, you signed with us until June 2020 and we're very happy for it," Galliani said in a statement.
"You're a young man, you're 20, and because of it we believe you have all the time in the world to become an icon of our club, following the path of the great rossoneri defenders.
"A big hug from all at AC Milan, and forza Alessio."
Romagnoli had earlier spoken of how much he is relishing the opportunity to kick on at Milan.
"It's all very exciting for me," he told the club's official website. "Milan are one of the most important clubs in the world. Now it's up to me to do well.
"Mr. Mihajlovic told me that if there was a chance, he would take me with him.
"Now I want to help the team and I will try to give my best, my all.
"With [Roma boss Rudi] Garcia I had a good relationship, he said he wanted to keep me for many reasons, but then the club has made the decision to sell me and I wanted to come to Milan."comments