The Inter striker has forged a bad-boy reputation in Italian football throughout his career, but the Bianconeri centre-back claimed Cassano is always embraced by his national team-mates.
“Here everyone feels at home and Antonio is always welcome,” said Chiellini.
“We are talking about a great guy and certainly we greet before Juve-Inter.
“He is kind and whimsical, but he is a good boy. Here there is a beautiful atmosphere [with the national squad] and Prandelli has already explained the motivation of the side."
Italy are currently four points clear of Bulgaria at the top of Group B in World Cup 2014 qualification, with 10 points to their name after beating Denmark 3-1 on Tuesday night.