Mancini said: "In one or two years he will become one of the best players in the world. He will be very popular with our fans.
"Balotelli in England could be fantastic and I don't think he will have a big problem here. He can play right wing, first striker, second striker. He's fantastic.
"He's only 20 but he is a strong character and a good guy."
Balotelli was the subject of racist taunts during his Serie A playing days and many of his problems are believed to stem from that.
Mancini added: "He has not always behaved so well - but he's a good man."