Leao penned terms to 2028 with Milan on Friday.
“I am very happy, extending the contract is what I wanted," Leao told the official club channel.
“I told the club and my teammates that my goal was to stay here. Eventually we managed to reach an agreement for me to continue here.
“Milano is my home, the day I arrived, everyone welcomed me with open arms. Everyone supported me during the difficult times. Here I can improve on a daily basis. I feel at home.
“Thanks to the faith in me, I can reach the top and win trophies here. Everybody at AC Milan is like a family to me, they are helping me big time in doing what I'm doing on the pitch.
“This enables me to be an important player for my team, which is what I had been looking for before coming to Milan."