Reso was born on November 30, 1973 in Kitchener, Ontario, the son of an American father and a Canadian mother. He played ice hockey and was a wrestling fan as a child. Reso lived in Huntsville and East Luther-Grand Valley before moving to Orangeville, where he met Adam Copeland, who became his best friend and eventual tag team partner. The two attended Orangeville District Secondary School together, from which Reso graduated.

When Copeland received a tryout match with the World Wrestling Federation (WWF), Reso went with him and they faced off in an untelevised tryout match, which Copeland was booked to win. After the tryout, once Copeland was promoted from his developmental status to touring with the WWF, he put in a good word for Reso and got him invited to the WWF-affiliated Dory Funk, Jr.'s Funking Conservatory training camp in 1998. After completing his training at the conservatory, Reso signed a contract with the WWF to become a full-time performer.

In 1999, Christian and Edge parted ways with Gangrel, who associated himself with The Hardy Boyz (Jeff and Matt Hardy) to form The New Brood. As a result, they began feuding with The Hardy Boyz and went on to compete in a ladder match for the managerial services of Terri Runnels and $100,000 at No Mercy on October 17, which The Hardy Boyz won. At Survivor Series on November 14, Edge and Christian and The Hardy Boyz faced Too Cool and The Hollys in a four-on-four Survivor Series elimination match, but they lost. At Armageddon on December 12, Edge and Christian competed in a eight-team battle royal which was won by The Acolytes. At the Royal Rumble on January 23, 2000, Christian competed in the Royal Rumble match, but he was eliminated by Rikishi. At No Way Out on February 27, Edge and Christian defeated The Hardy Boyz in a tag team match to determine the number one contenders to the WWF Tag Team Championship. At WrestleMania 2000 on April 2, Edge and Christian defeated The Hardy Boyz and The Dudley Boyz (Bubba Ray and D-Von) to win their first WWF Tag Team Championship in a triangle ladder match, which ultimately led to the creation of the Tables, Ladders and Chairs (TLC) match. At Backlash on April 30, Edge and Christian defeated Road Dogg and X-Pac to retain titles. At Judgment Day on May 21, Christian, Edge and Kurt Angle lost a six-man tag team match to Rikishi and Too Cool, to whom they lost the titles soon after only to win them back in a four corners elimination match at King of the Ring on June 25. At Fully Loaded on July 23, Edge and Christian lost to The Acolytes Protection Agency (Bradshaw and Faarooq) by disqualification, but they retained the titles.

Reso currently lives in Tampa, Florida, with his wife Denise, a German model whom he met while on tour in England. The couple married on May 25, 2001. On December 9, 2013, Reso announced on WWE.com that he had taken time off due to recurring post-concussive symptoms and during the time off his wife gave birth to their first child, a daughter named Isla.

Following WrestleMania X8, Christian formed an alliance with fellow Canadian Wrestlers Lance Storm and Test in June 2002, calling themselves The Un-Americans and winning now named WWE Tag Team Championship (formerly the WWF Tag Team Championship, which was renamed due to the WWF being forced to rename itself World Wrestling Entertainment) at Vengeance on July 21, but they lost the titles on the September 23 episode of Raw to the team of The Hurricane and Kane. Christian later formed a tag team with Chris Jericho and competed in a fatal four-way tag team TLC match for the WWE Tag Team Championship on the October 7 special episode of Raw Roulette, but they failed to win the titles only to win them (renamed World Tag Team Championship) on October 14. At Armageddon on December 15, Christian and Jericho lost the titles in a fatal four-way elimination match involving the teams of The Dudley Boyz, Booker T and Goldust and Lance Storm and william Regal.

In 2003, Christian self-proclaimed himself as the new "People's Champion" and began calling his fans "The Peeps" after receiving advice and endorsement from The Rock. On the May 5 episode of Raw, Christian faced Goldberg, but the match ended in a no contest when 3-Minute Warning got involved which led to a rematch on May 12, where Christian lost to Goldberg in a steel cage match. At Judgment Day on May 18, Christian went on to win a nine-man over-the-top-rope battle royal for the vacant Intercontinental Championship. The following night on Raw, Christian appeared on Chris Jericho's talk show The Highlight Reel sporting a new haircut and ring attire. Christian lost the Intercontinental Championship to Booker T on the July 7 episode of Raw, but he regained the title after Booker was legitimately injured at a house show on August 10. At Unforgiven on September 21, Christian defeated Jericho and Rob Van Dam to retain the title in a triple threat match, but he lost the title to Van Dam in a ladder match on the September 29 episode of Raw. At Survivor Series on November 16, Christian was a part of Team Bischoff taking on Team Austin and during the match eliminated Bubba Ray Dudley before being was eliminated by Shawn Michaels, though in the end Team Bischoff won the five-on-five Survivor Series elimination match. At Armageddon on December 14, Christian and Jericho defeated Lita and Trish Stratus in an intergender tag team match billed as the "Battle of the Sexes".

Also in 2003, Christian and Christian began romances with Lita and Stratus, respectively; and as part of the angle it was revealed to be a bet over who could sleep with their respective female first, with a Canadian dollar at stake. Despite the bet, Jericho continued his relationship with Stratus, which ultimately resulted in Christian and Jericho turning on each other. At the Royal Rumble on January 25, 2004, Christian competed in the Royal Rumble match, but he was eliminated by Jericho. At WrestleMania XX on March 14, Christian faced Jericho in a singles match with Stratus on Jericho's side, but Stratus accidentally struck Jericho, allowing Christian to defeat him. Stratus then joined forces with Christian, becoming his on-screen girlfriend in the process. At Backlash on April 18, Christian and Stratus faced Jericho in an intergender handicap match which they lost. During a steel cage match against Jericho on the May 10 episode of Raw which he lost, Christian suffered a severe back injury, causing him to miss almost four months of in-ring action. Christian returned on the August 30 episode of Raw, resuming his feud with Jericho and ending it in a ladder match for the vacant Intercontinental Championship at Unforgiven on September 12.

On the April 8 episode of SmackDown, Christian lost to Del Rio in a number one contender's match for the World Heavyweight Championship after a distraction from Brodus Clay. After Edge's sudden retirement from wrestling on the April 15 episode of SmackDown, Christian won a 20-man battle royal to face Del Rio for the vacant World Heavyweight Championship at Extreme Rules on May 1, where Christian defeated Del Rio to win the World Heavyweight Championship. On the May 6 episode of SmackDown, Christian lost the World Heavyweight Championship to Randy Orton. At Over the Limit on May 22, Christian failed to regain the championship from Orton. On the June 3 episode of SmackDown, Christian was the special Referee for a World Heavyweight Championship defense by Orton against Sheamus, which Orton won only to be hit by Christian after the match with the title belt, turning into a villain for the second time since 2005. At Capitol Punishment on June 29, Christian faced Orton for the World Heavyweight championship once again, but he failed to capture the title. At Money in the Bank on July 17, Christian won the World Heavyweight Championship after Orton was disqualified for kicking him in the groin (the stipulation was if Orton was disqualified or the Referee made a bad call, he would lose the title). At SummerSlam on August 14, Christian lost the World Heavyweight Championship to Orton in a No Holds Barred match. On the August 26 episode of SmackDown, special guest General Manager Bret Hart announced that Christian would face Orton in a steel cage match on the August 30 episode of SmackDown for the title, which Christian lost to end their feud. Christian then began feuding with Sheamus, leading to a match between the two at the Hell in a Cell on October 2 and Vengeance on October 23, both of which Christian lost.

Reso has been a playable character in most of WWE video games starting from WWF Attitude until WWE SmackDown! vs. Raw 2006 and then reappearing in WWE SmackDown vs. Raw 2010 and appears in WWE SmackDown vs. Raw 2011, WWE '12, WWE '13, WWE 2K14, WWE 2K15, WWE 2K16, WWE 2K17 and WWE 2K18. He also appeared in TNA iMPACT! video game in 2008. In 2007, TNA Home Video released a DVD titled The Instant Classic: Christian Cage, covering his beginnings in the independent circuit and other various subjects up to his second NWA world title reign. Reso is also the host of the DVD The Ladder Match 2: Crash and Burn. In September 2015, Edge and Christian were guests on the Stone Cold Steve Austin Podcast, which aired on the WWE Network.

Abyss was later kicked out of the group after he attacked Cage on the April 19 episode of Impact!. Steiner was the next to leave the group after he was attacked by Tomko following their tag team title match at Sacrifice. Cage was set to defend the NWA world title against Sting at Sacrifice, but Angle was added to the match on the May 3, 2007 episode of Impact!, making it a three-way match. At the event on May 13, the National Wrestling Alliance (NWA), the owners of the NWA World Heavyweight and the NWA World Tag Team Championships, stripped Cage and Team 3D of the titles. NWA Executive Director Robert K. Trobich stated the reason was that Cage refused to defend the NWA world title at NWA live events. Cage, still holding the physical NWA world title belt, defended what was billed as the World Heavyweight Championship against Sting and Angle, who was the Victor of said contest by making Sting submit (who had "technically" just pinned Cage at the very same moment) and was announced as the new World Heavyweight Champion. On the following episode of Impact!, Angle came to the ring with a new championship belt in-toe and announced he was the new TNA World Heavyweight Champion, a championship that TNA had just introduced at Sacrifice. Afterwards, Cage and Sting came to the ring and the three began to argue over who was the new TNA World Heavyweight Champion, but due to the controversial finish to their match at Sacrifice the title was declared vacant by Cornette and a tournament was held for the title which culminated in a King of the Mountain match at Slammiversary on June 17. Cage won entry into the match on the June 14 episode of Impact! by defeating Abyss. Cage failed to defeat the four other men (Styles, Joe, Angle and Chris Harris) and win the title as Angle hung the title belt to become the new and undisputed TNA World Heavyweight Champion.

After defeating Harris at Victory Road on July 17 and him, Tomko and Styles losing to the team of Andrew Martin, Sting and Abyss at Hard Justice on August 12 in a Doomsday Chamber of Blood match to become number one contender to the TNA World Heavyweight Championship, Cage restarted his feud with Samoa Joe and the two met at No Surrender on September 9, where he defeated Joe by disqualification when Joe refused to release his rear naked choke submission hold he had applied. The two had a rematch with Matt Morgan as the special outside enforcer at Bound for Glory on October 14, where Cage lost to Joe and ended his 23-month-long undefeated streak by not officially being pinned nor made to submit. Cage and Joe fought one more time on the October 18 episode of Impact!, with a spot in the 2007 Fight for the Right tournament to become number one contender to the TNA World Heavyweight Championship. Cage defeated Joe to gain entry. Cage made it all the way to the final round of the tournament, where he fought Kaz on the November 8 episode of Impact!, defeating Kaz due to interference from Styles and Tomko on Cage's behalf, but the match was declared a no contest, with the finals being determined in a ladder match at Genesis on November 11. However, Cage failed to win the tournament final the second time around at Genesis. Later in the night, Styles and Tomko helped Angle retain the TNA World Heavyweight CHampionship during the main event as Cage looked on from the ramp. Styles and Tomko were later announced as members of Angle's new group, The Angle Alliance, which led to a title match between the two at Final Resolution on January 6, 2008 and also turning Cage into a fan favorite in the process.

During an interview with TNA President Dixie Carter in January 2009, she confirmed that Reso's contract with TNA had expired and that he had re-signed with the World Wrestling Entertainment (WWE). Reso did not appear for the promotion until the February 10 episode of ECW under his old ring name Christian, confronting then ECW Champion Jack Swagger as a fan favorite. Later that night, Christian defeated Swagger in his first match back. On the February 24 episode of ECW, Christian faced Swagger again for the ECW Championship in a losing effort. Christian won a tri-branded 15-man battle royal on the March 10 episode of ECW, gaining entry into the Money in the Bank ladder match at WrestleMania XXV on April 5, which he failed to win.

On the August 4 episode of ECW, Christian retained the ECW title in an Extreme Rules match against Dreamer. Christian then began a rivalry with william Regal over the ECW Championship, retaining the title against him at SummerSlam on August 23. and at Breaking Point on September 13. After a few months of defending the ECW Championship on ECW only, retaining the title against the likes of Zack Ryder and Yoshi Tatsu, Christian was part of Team Kingston in a Survivor Series elimination match at Survivor Series on November 22, where he eliminated both Ted DiBiase and Cody Rhodes before being eliminated by Randy Orton. At TLC: Tables, Ladders & Chairs on December 13, Christian successfully defended the title against Shelton Benjamin in a ladder match. In late December 2009, Christian became the longest reigning WWE-era ECW Champion. At the Royal Rumble on January 31, 2010, Christian successfully defended the ECW title against Ezekiel Jackson. On February 16, Christian lost the ECW title in an Extreme Rules match to Jackson on the final episode of ECW.

In September 2010, Christian tore his pectoral muscle and was expected to be sidelined for approximately six months. Following surgery, WWE released a statement that revealed he was expected to only be sidelined for four months. The injury was put into a storyline with Alberto Del Rio attacking Christian backstage on the September 24 episode of SmackDown. Christian made his return from injury at Elimination Chamber on February 20, 2011, saving Edge from an attack by Del Rio. On the March 4 episode SmackDown, Christian saved Edge from another attack by Del Rio. On the March 7 episode of Raw, Christian made his in-ring return from injury against Del Rio's bodyguard Brodus Clay, picking up the victory. On the March 11 episode of SmackDown, Christian reunited with Edge and defeated Del Rio and Clay in a tag team match. On the following episode of SmackDown, Christian defeated Del Rio in a steel cage match, but was afterwards attacked by both Del Rio and Clay. Christian was in the corner of Edge when he retained the World Heavyweight Championship against Del Rio at WrestleMania XXVII on April 3.

At Elimination Chamber on February 19, 2012, Christian returned from his injury to show support for John Laurinaitis. Christian returned on the March 16 episode of SmackDown, hosting an episode of The Peep Show and given a spot on Laurinaitis' team in a 12-man tag match at WrestleMania XXVIII on April 1. On the March 26 episode of Raw, Christian was injured once again after (kayfabe) re-aggravating his neck and shoulder in a match with CM Punk. This was to write him off at WrestleMania XXVIII as it was later reported that Christian has not yet been fully medically cleared to compete due to a history of shoulder injuries. Despite the injury, Christian still appeared at the WWE Hall of Fame ceremony to induct long-time friend Edge.

After a ten-month absence, Christian returned from injury on the June 17, 2013 episode of Raw, defeating Wade Barrett. Later that week on SmackDown, Christian was attacked by The Shield while delivering a promo after defeating Drew McIntyre. On the June 26 episode of Main Event, Christian took on Shield member Dean Ambrose, which resulted in a disqualification win for Christian following interference from Ambrose's stablemates, Seth Rollins and Roman Reigns. That same week on SmackDown, Christian teamed up with The Usos to defeat The Shield, handing the stable their second loss in six-man tag team matches. At Money in the Bank on July 14, Christian competed in the WWE Championship Money in the Bank ladder match, but was unsuccessful as the match was won by Randy Orton. During the match, Christian had his teeth chipped after a strong punch from Sheamus through the rungs of a ladder. On the July 29 episode of Raw, Christian defeated World Heavyweight Champion Alberto Del Rio in a non-title match. That same week on SmackDown, Christian defeated Randy Orton and Rob Van Dam in a triple threat match to become number one contender to the World Heavyweight Championship, after which he was attacked by Del Rio during a post-match interview. On the August 9 episode of SmackDown, Christian again defeated Del Rio in a non-title match. At SummerSlam on August 18, Christian failed in his title challenge against Del Rio. On the September 9 episode of Raw, The Shield dragged out an assaulted Christian as a message to anyone that disrespected Triple H following Edge's opinion on Triple H's recent abuse of power. On that week's SmackDown, Edge promised Christian would return soon and get his payback. Christian returned and appeared on the 2013 Slammy Awards, where he presented an award and appeared in a segment involving John Cena and Randy Orton.

After suffering his concussion, Christian appeared on pre-show discussion panels for WWE for events including NXT TakeOver, Money in the Bank and Battleground. In 2014, he went on to host The Peep Show program with Chris Jericho at Night of Champions in September and with Dean Ambrose on the November 7 episode of SmackDown.

Edge and Christian were the guest hosts for the December 29 episode of Raw, where WWE commentator Jerry Lawler referred to Christian as "retired". Pro Wrestling Insider corroborated Lawler's statement, adding that because of multiple concussions and other injuries, the company considered Christian retired as an active Wrestler. On October 27, 2015, Christian's profile was moved to the alumni section at WWE.com and noted that he had left active competition. On the March 2, 2016 episode of Talk Is Jericho, Christian said that while he has had no formal discussion with management regarding his retirement, he is unlikely to wrestle again. He confirmed his status on the September 22, 2017 edition of E&C's Pod of Awesomeness, saying: "I had to retire, like, right around 40... 'cause of the concussion stuff".

In mid-May 2016, it became known that Reso had been released from his talent contract. On the June 22, Talk Is Jericho podcast focusing on the Chris Benoit tragedy, Jericho mentioned Christian as an Example of modern Wrestlers who had to retire as the WWE would no longer give them medical clearances due to concussion related injuries (this was largely as a consequence of the Benoit incident as well as better knowledge of chronic traumatic encephalopathy (CTE) and other concussion related risks).

In January 2018, Christian made a one-night return to WWE, hosting The Peep Show with special guests Jason Jordan and Seth Rollins, but it was later interrupted by The Bar (Cesaro and Sheamus).