Brian Adams and Bryan Clark first joined together as a duo in April 2000 in World Championship Wrestling (WCW). Upon joining together as a tag team, KroniK (originally spelled Kronic) assisted Vince Russo in his vision of a clean sweep for his New Blood alliance at the 2000 Spring Stampede pay-per-view. Adams and Clark interfered in the WCW World Tag Team Championship match, allowing the team of Buff Bagwell and Shane Douglas to win the title.
While in WCW, KroniK moved between babyface and heel roles several times - holding the WCW Tag Team Championship twice. In the final months of WCW, KroniK became hired muscle. Their contracts were not picked up by the WWF when WCW went out of business.
In September 2001, Brian Adams and Bryan Clark each made their re-debut as a World Wrestling Federation (WWF) tag team. Recruited by Stevie Richards, KroniK was called in to settle past differences Richards had with The Undertaker, stemming from the disbanding of Richards' stable, "Right to Censor" earlier that year. KroniK wrestled their first tag team match defeating Kaientai on the September 20, 2001 episode of SmackDown and their last tag team match for WWF a few days later at Unforgiven, losing to then-WCW Tag Team Champions The Brothers of Destruction (Kane and The Undertaker).
After two dark matches, four appearances on Raw and SmackDown, and a pay-per-view appearance, Clark was released from his contract, ending the tag team. Adams would be released as well in November 2001.