The 31-year-old has been confirmed as a Rossoneri player, with Djamel Mesbah and Rodney Strasser making the switch in the other direction to Parma
The former Italy international has made the switch to San Siro with Djamel Mesbah moving in the other direction on a permanent basis, with Rodney Strasser going to the Ennio Tardini on loan.
Zaccardo has spoken of his pride at joining such a big club, and vowed to give his all in order to help the Rossoneri during his time there.
"I am proud to have joined Milan. The negotiations started a few weeks ago and now I am here," he told the club's official TV channel.
"I can play in the centre of defence or at full-back and I will give my best. I am 31 and I come here after playing a lot of matches in Serie A. I know some of the players and I will meet the rest on Friday."
Milan travel to Atalanta on Sunday as they look to keep up their pursuit of silverware.