In 2002, Danielson joined the independent promotion Ring of Honor (ROH), where he is acknowledged as a "Founding Father" of the company. On February 22, he competed in the main event of the company's debut event, The Era of Honor Begins, in a three-way match against Christopher Daniels and Low Ki. One of his matches with Austin Aries, performed on August 7, 2004 at Testing the Limit, lasted seventy-four minutes before Aries was finally declared the victor. 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.