Keane, who played 480 games for United from 1993 to 2005, told the Daily Star: "Sir Alex Ferguson will be a big help for David Moyes.
"As a top manager he will appreciate that he doesn't have all the answers and he will go to Ferguson asking for some guidance.
"That's a sign of strength, not weakness.
"I think Moyes is an excellent choice. I nearly signed for him when I left United and he was at Everton.
"I've come across him and he's got a bit of class.
"He seems very honest and he doesn't talk nonsense like some of the other managers out there. I think he'll do a great job."