Berlusconi had been battling Leukaemia and spent a significant amount of time in hospital in his last days.
Berlusconi, who completed four terms as Prime Minister of Italy, took over a struggling AC Milan side in 1986 and turned them into a major force in domestic and European football.
Under Berlusconi's ownership, AC Milan won eight Serie A titles and five European Cups.
He ceded control of Milan in 2017 and took over at Monza, leading them into Serie A for the first time in the club's history.
Milan said in a statement on their Twitter account: “Deeply saddened, AC Milan grieves the passing of the unforgettable Silvio Berlusconi and wishes to reach out to the family, associates, and most cherished friends to share our sympathies.
“Tomorrow, we will dream of new ambitions, create new challenges and seek new victories. Which will represent the good, the strong, and the true that lies inside us, in all of us who shared this adventure of binding our lives to a dream called Milan. Thank you, Mr President. Always with us.”
Carlo Ancelotti, who played for and later managed Milan during Berlusconi’s reign, posted a message of sympathy.
“Today’s sadness doesn’t erase the happy moments spent together,” wrote Ancelotti, who won two league titles and two European Cups as a player at the San Siro before going on to lead them to the league title and two Champions League successes as manager.
“There remains infinite gratitude to the president, but above all to an ironic, loyal, intelligent, sincere man, fundamental in my adventure as a football player first, and then as a coach. Thank you President.”
