Balotelli is the talk of Italy after his brace on debut in victory over Udinese.
"He seems to have already changed his image," Prandelli said. "He was smiling and laughing a lot when he arrived.
"He's already found that serenity which he lost in England, where he didn't play a lot and he was forced to deal with a lot of non-football issues.
"Now he'll get more regular games and he'll thus find form. It all depends on him. Mario can only get better as he has margins of improvements to make.
"I said that we were obliged to believe in him because players like him don't pop up very often."