The Italian has been linked with a January move to Chelsea, but Galliani has backed coach Massimiliano Allegri and made it clear that Balotelli is at the club for the long term.
"Mario Balotelli will not leave Milan," Goal.com quotes Galliani as saying.
"He will stay with us for many years, and he is our star. He has a long contract and he will see it out."
Milan have struggled at the start of the new season and currently sit 10th.