Ruben Studdard Files for Divorce

"American Idol" champ Ruben Studdard has filed for divorce, TMZ has learned.

The Velvet Teddy Bear (who won Season 2 back in 2003) filed the papers in Alabama ... citing -- what else -- "irreconcilable differences."

Ruben and his wife Surata Zuri McCants tied the knot in 2008. They have no kids.

A rep for Studdard tells us, “Ruben and Zuri have gone their separate ways.”