The Rossoneri coach says the arrival of the flamboyant striker was vital in their third-placed finish
The Italy international joined the Rossoneri from Manchester City in the January transfer window and netted 12 goals in 13 league appearances.
His strikes helped fire Milan to a third-placed finish in Serie A, giving them a total of 72 points, having previously struggled to reach the top half of the league before December.
"After we reached our main objective of qualifying for the Champions League knock-outs, the team grew," Allegri said at a press conference.
"We played some young players and then the arrival of Balotelli was the icing on the cake. We needed that individual quality.
"So the transfer market in January was fundamental in us meeting our objective, just like it was in the season that we won the Scudetto."
Allegri was recently confirmed as Milan's head coach for next season after a meeting with Silvio Berlusconi and club CEO Adriano Galliani.