Christian made his professional wrestling debut in June of 1995, wrestling on the Canadian independent circuit. During his tenure in these federations he teamed with Edge, his brother according to the storyline. In August 1998, he signed a developmental contract with the then World Wrestling Federation and quickly captured his first title, the Light Heavyweight Championship, by defeating Taka Michinoku.

He later reunited with Edge, with whom he won the World Tag Team Championship seven times between 2000 and 2001; during this period the two gained much popularity in the tag division, especially for their participation in three spectacular Tables, Ladders & Chairs matches against the Dudley Boyz and the Hardy Boyz.

Over the course of his career, he has won twenty-three titles between WWE and TNA.

He is a seven-time world champion, having each held the NWA World Heavyweight Championship twice, the ECW World Heavyweight Championship, the WWE World Heavyweight Championship and the Impact World Championship once; he has also captured the Light Heavyweight Championship, the Hardcore Championship, the European Championship, the Intercontinental Championship (four times) and the World Tag Team Championship (nine times). In addition to these accolades, Reso is the twenty-third wrestler in WWE history to complete the Triple Crown and the twelfth to reach the Grand Slam.