After Danielson graduated from high school in 1999, he decided to pursue wrestling professionally and attempted to train at Dean Malenko's wrestling school.When it closed he trained under Shawn Michaels and Rudy Gonzalez at the Texas Wrestling Academy (TWA).Danielson went on to make four additional non contracted appearances for WWE in 2003 on its secondary programming, Velocity and Heat, initially as enhancement talent before being allowed to compete in longer matches; he wrestled Jamie Noble at a Velocity taping in January, Rico at a Heat taping in February, John Cena at a Velocity taping also in February and making his final appearance in November in a tag team match against Paul London and Spanky at a Velocity taping in which Danielson was partnered with John Walters.
He was the first winner of ROH's annual Survival of the Fittest tournament in 2004.
Danielson also wrestled extensively in Japan, winning the GHC Junior Heavyweight Championship in Pro Wrestling Noah and the IWGP Junior Heavyweight Tag Team Championship (with Curry Man) in New Japan Pro-Wrestling (NJPW).
Danielson first toured Japan with Frontier Martial-Arts Wrestling (FMW) with Lance Cade, a fellow trainee from the TWA, competing in several tag team matches.
He returned to Japan after his release from the WWF, competing in Japan's premier promotion, New Japan Pro-Wrestling (NJPW), where he used his American Dragon persona and donned a red, white and blue mask reminiscent of a dragon.
In February 2016, Danielson retired from professional wrestling due to medical issues (including seizures) arising from multiple concussions and a brain lesion.
That July, he became the Smack Down General Manager following the return of the brand extension.three times and WWE's World Heavyweight Championship once, in addition to being a one-time United States Champion, a one-time Intercontinental Champion and a one-time WWE Tag Team Champion as part of Team Hell No (with Kane).He was also the 2011 Smack Down Money in the Bank winner and the 2013 Superstar of the Year Slammy Award winner.As a part of the junior heavyweight division, Danielson had success in both singles and tag team competition in the company, winning (without wearing a mask) the IWGP Junior Heavyweight Tag Team Championship with Curry Man on March 12, 2004.One of the more notable rivalries he had in the early years in the company was with Homicide, as the two fought numerous matches with a variety of stipulations, culminating in a steel cage match on May 13, 2005 at The Final Showdown, where Danielson was victorious.Despite winning the company's inaugural Survival of the Fittest tournament in 2004, he had not yet won a ROH title.