"He's a very good player and a valuable member of our team," Carsley told evertonTV.
"It bodes well for the future of the club because he's still a young player and, of course, he came through the ranks here with Tony Hibbert so it's nice to see them both doing so well."
Osman gave another fine account of himself against Real Salt Lake at the weekend and Carsley believes that his pal should get more credit for the quality of his displays.
"I think Ossie is a very under-rated player but he does really well for us," said the Republic of Ireland midfielder.
"He's grown into his role in the team and is someone that we really appreciate."