The Italy international will not feature for the Rossoneri at the weekend when they take on Serie A's third-placed team in a crucial match.
The former Manchester City attacker picked up a leg injury earlier this week, and he will not be recovered in time for Saturday's encounter at San Siro. The match his a huge one for Milan's UEFA Champions League aspirations, as the club trails Lazio by two points for third place and could move into the coveted spot in the table with a victory.
"Balotelli will not be available due to a bruised tibia. Unless something miraculous happens between now and Saturday morning, he will not feature against Lazio," Allegri said at a press conference.
The 22-year-old striker's absence will come as a huge blow to Milan as he has become a key player for the Rossoneri since his winter move. Balotelli has scored four goals in as many Serie A appearances for the 2011 Italian champions since his estimated 22 million euro switch from Man City.