AC Milan goalkeeper Gianluigi Donnarumma gifted two goals and Nikola Kalinic added an own-goal in a nightmare 4-0 defeat for the Rossoneri as Juventus claimed a record fourth straight Italian Cup title on Wednesday.
While the 19-year-old Donnarumma could not be blamed for Medhi Benatia's opener in the final, his mistakes led to the ensuing goals from Douglas Costa and Benatia. Then Kalinic headed a corner into his own net.
After the final whistle, Milan captain Leonardo Bonucci and Juventus counterpart Gianluigi Buffon attempted to console Donnarumma.
"We have to accept it and realise we made our own errors," Milan coach Gennaro Gattuso said.
Juventus defender Mehdi Benatia scored a brace.
The Moroccan struck before and after a searing Douglas Costa drive to seal Juve's win between the 56th and the 64th minutes.
It was the first of two titles that Juventus are hoping to celebrate over the space of four days at the Stadio Olimpico.
The Bianconeri can clinch a record-extending seventh consecutive Serie A title with only a draw against Roma on Sunday.
"Now we have to ensure the Scudetto mathematically and enjoy this extraordinary season," Juventus coach Massimiliano Allegri said.
Juventus has won a total of 13 Italian Cups, at least four more than any other team.
Milan, meanwhile, missed out on a chance to justify its pre-season spending spree and take home a trophy ahead of likely punishment from UEFA for financial fair play violations.