The Milan chief insists that the 18-year-old will not leave the Italian giants this summer, despite the players confirming last week that he would not sign another contract with the club.
The strapping stopper has been linked with a move to some of Europe's top sides, including, Juventus, Real Madrid, PSG and Manchester United.
However, in an interview with 'Milan TV' Fassone insisted that "Donnarumma is staying here", "without doubt he will stay and next year he will be free to make a decision."
Fassone did admit that Milan would listen to offers for their wantaway star but insisted that the club would not be held to ransom and that derisory offers of £15million or £20million would simply not be entertained. He ended the interview by saying "we are open to offers. We will look at them all but our project is clear. Donnarumma stays."