Kaka - who returns to the San Siro after a four-year period at Real Madrid - will replace Stephan El Shaarawy in the starting 11 at the Stadio Olimpico in Turin.
El Shaarawy will miss the league clash due to a right thigh issue, which will also sideline him for their UEFA Champions League battle with Celtic at home.
"Over the next few days the player (El Shaarawy) will undergo further tests to stabilise a prognosis and recovery time," a club statement read.
Allegri all but confirmed the 31-year-old Brazilian Kaka will start against Torino - who are level on three points with the Milanese side through two games.
"I think he will be in the starting 11. He is in good shape, he has trained really well and he has the enthusiasm of a young boy," Allegri said of Kaka.
"I think he is a little nervous about his debut tomorrow and it is only normal that he is missing a bit of match sharpness. Kaka can give a lot to Milan.
"He has done some great things here at this club, he hasn't played a lot over the last three years in Madrid, but he has immediately put himself at my disposal.
"He spends a lot of the day at Milanello and he is a great example for the youngsters."
