Mancini believes the 20-year-old will become a bigger star than Liverpool striker Fernando Torres.
Balotelli joined City from Italian side Inter Milan last week.
“I think that Balotelli could be as good as Torres and even better than him,” explained Mancini.
“That’s because Torres can only play as a striker. Balotelli can play as a striker and as a winger. He has a different attitude from Torres.
“But what is sure is that we are talking about two fantastic players.”
“The defenders do not know much about him but they will see he can change everything about a game,” added the Italian coach.
“I saw him four years ago when I was at Inter Milan. He was 16 or 17.
“It was the last five games of the Serie A championship. We had (Zlatan) Ibrahimovic injured and we played Mario inside and he played like someone who was 30 years old.
“That’s because he has good technique, he has everything. Yes, he is a good signing for us.”