The Rossoneri official says the 23-year-old will stay at San Siro for the long-term, amid rumors he could be reunited with his former mentor Jose Mourinho.
The 23-year-old has been linked with a surprise move to Stamford Bridge, despite not enjoying the best of relationships with Jose Mourinho during their time together at Inter.
And Galliani has moved swiftly to halt any talk of the Rossoneri's star man leaving the club and even predicted he would remain at San Siro for a long time to come.
"Mario Balotelli will not leave Milan," he told reporters. "He will stay with us for many years, and he is our star. He has a long contract and he will see it out."
Galliani also discussed the ownership of the club in light of the recent takeover of city rivals Inter by billionaire Erick Thohir.
"There has been no kind of contact whatsoever, because the club is not for sale. Even more so now that the accounts are matched," he said.
The 69-year-old also assured coach Massimiliano Allegri that his job is safe, although he admits the situation will be reassessed next summer.
"Allegri will remain our coach," he added. "At the end of the season we will see how things have gone and assess our options then. I spoke with [Riccardo] Montolivo and told him that, as captain, I expect better. I was also unhappy with [Valter] Birsa, who I expect to see play as well on Saturday's and Sunday's as he does in training."