Danielson was previously signed to the WWE, then known as the WWF, for an 18-month period from 2000–2001. Prior to joining WWE for his second stint in 2009, Danielson wrestled for various companies internationally using both his real name and the ring name (and later nickname) "American Dragon". He wrestled for Ring of Honor (ROH) from 2002 to 2009, being recognized as a "Founding Father" of the promotion, where he was a one-time ROH World Champion, as well the final Pure Wrestling Champion (unifying the Pure title with the World title). He was the first winner of ROH's annual Survival of the Fittest tournament in 2004. Along with CM Punk, Seth Rollins and Kevin Owens, Danielson is one of four men to have won a world championship in both WWE and ROH.
Danielson also wrestled extensively in Japan, winning the GHC Junior Heavyweight Championship in Pro Wrestling Noah (NOAH) and the IWGP Junior Heavyweight Tag Team Championship (with Curry Man) in New Japan Pro Wrestling (NJPW). Between WWE, ROH, and Japanese promotions, he held eleven total championships, including five world titles. Danielson also won numerous titles on the independent circuit, including two PWG World Championships, the FIP Heavyweight Championship, and the wXw World Heavyweight Championship.
In 2016, at age 34, Danielson retired from professional wrestling due to medical issues (including seizures) arising from multiple concussions and a brain lesion. Later that year in July, he was named the General Manager of SmackDown following the return of the WWE brand extension. In August 2017 following multiple consultations from doctors he was cleared to return to in ring action with the WWE.
Labelled a "wrestling genius" by journalist Dave Meltzer, he was inducted into the Wrestling Observer Newsletter Hall of Fame class of 2016.