Allegri won his first award in 2008/09 when he managed Cagliari, and then at the helm of the Bianconeri, winning in 2014/15 and 2016/17.
17 votes clinched the prize, surpassing both Maurizio Sarri and Simone Inzaghi, who came in tied in second place with eight votes each.
"It's an honour and a privilege - said Allegri after the award ceremony - I thank the club, the players and my staff, which makes my job easier, as they are always the architects of these victories. What will it take to win the next one? We have to try to win the eighth title, which is the main objective. Then there's the Champions League, we've played in two finals, facing the two strongest teams at the time. We'll see if this year luck will give us a helping hand, now we have to work hard to move forward. From March, it will be a different competition."