American investment group RedBird Capital has completed a deal to buy AC Milan from Elliott Advisors.
The deal values AC Milan, current Serie A champions, at 1.2bn euros (£1bn).
As part of the agreement, Yankee Global Enterprises, owners of baseball team the New York Yankees, will take a minority stake in the club.
RedBird is a co-owner of the Yankees Entertainment Sports (YES) Network, the most-watched regional sports network in the United States.
Gerry Cardinale, RedBird founder, said the investment group's partnership with the New York Yankees would help them "explore opportunities together to broaden our fan reach and expand commercial opportunities globally".
He added: "Our vision for Milan is clear: we will support our talented players, coaches and staff to deliver success on the pitch and allow our fans to share in the extraordinary experiences of this historic club.
"We will look to leverage our global sports and media network, our analytics expertise, our track record in sports stadium developments and hospitality to deliver one goal - maintaining Milan's place at the summit of European and world football."
RedBird's sporting portfolio, which is worth $7.5bn (£6.5bn), includes stakes in Fenway Sports Group, the owners of Liverpool and baseball team the Boston Red Sox, as well as French Ligue 1 side Toulouse and IPL cricket team Rajasthan Royals.
When the deal for AC Milan was agreed in June it was confirmed that Elliott Advisors, who took over the club from Chinese businessman Li Yonghong four years ago, would retain a minority stake and seats on the board.
AC Milan celebrated their first Serie A title in 11 years in May and are unbeaten this season, sitting third in the table behind city rivals Inter Milan and league leaders Roma, having won two and drawn two of their opening four games.