The striker joined the Serie A side earlier this week, ending his two-and-a-half-year stint with Manchester City.
The 22-year-old, who previously played for AC's local rivals Inter Milan, told reporters: "It is an honour to play for Milan. I hope I'll stay here as long as possible. I'm here to win as a main player.
"Now is the best moment to be at AC Milan. My physical conditions are perfectly fine. To be back in Milan is important since I'm close to my family and friends and playing for Milan is a dream. I'd rather play than talk.
"I wasn't expecting such a welcoming from fans, it was very emotional. I'd celebrate during the derby if I score."
Balotelli scored 30 goals in 80 games with the Premier League champions.