"The entire history of AC Milan is in tears following the passing of Franco Baresi. His example and integrity will be forever etched into the Club's DNA, just as his iconic number 6 shirt is," the club said on social media website X.
Last year Baresi's former club, where he served as honorary vice president, said he had undergone surgery to remove a pulmonary nodule, and had been prescribed recovery treatment by a cancer specialist.
In February, Baresi was one of the torchbearers for the Olympic flame at the opening ceremony for the Milano Cortina Winter Games, appearing alongside former Inter Milan and Italy defender Giuseppe Bergomi, his longtime rival on the pitch.
Baresi is regarded as an AC Milan icon, having spent his entire 20-year career with the club, winning six Serie A titles and three top European trophies, and captaining the team for 15 seasons before retiring in 1997.
At the end of his playing career, Milan retired his number six shirt, making him the first player in the club's history to receive that honour.
'The Invincibles'
Baresi was part of the Italy squad that won the 1982 World Cup and captained the team to the 1994 final, which ended in a narrow penalty shootout loss to Brazil, with Baresi among the players who failed to score.
He famously played the full 120 minutes just 25 days after knee surgery.
His loyalty to Milan was established early in his career, as he stayed with the club through two relegations to Serie B in the early 1980s and helped guide them back to the top flight on both occasions.
Baresi was the cornerstone of the Milan and Italy defences for nearly two decades, captaining the Serie A club during the most successful period in their history and earning 81 caps for the national team.
In an era dominated by physical defenders, Baresi distinguished himself through his reading of the game, redefining the sweeper role by combining defensive authority with the ability to launch attacks from deep.
He marshalled a celebrated Milan backline featuring Paolo Maldini, Alessandro Costacurta and Mauro Tassotti, helping perfect the high defensive line and offside trap that underpinned the club's 58-match unbeaten run in Serie A and earned Fabio Capello's side the nickname "Gli Invincibili" (The Invincibles).