Simon turned pro in 1994 and won the WBO Light Middleweight title in 1998 by defeating Winky Wright by controversial decision. The bout had initially been ruled a draw, but then a "scoring error" favoring Simon was discovered. He defended the title four times against Kevin Lueshing, Enrique Areco, Rodney Jones and Wayne Alexander. He later captured the WBO Middleweight title against Sweden's Armand Krajnc in a unanimous 12-round decision. In 2002 Simon was involved in a serious car accident, sustaining injuries that prevented his defending his title; because of this he was stripped of the belt.