In September 1998 McGuinness began training under Les Thatcher in the Heartland Wrestling Association (HWA) in Cincinnati, Ohio, incurring large debts in the process. After debuting in September 1999, defeating GQ Masters III in a match that was featured on ABC's20/20, he spent a year wrestling in the mid west. McGuinness returned to England where he worked two full time jobs to earn enough money to be able to return to the U.S. to wrestle, and wrestled for All Star promotions between September and December 2001, where he learned from wrestlers such as Robbie Brookside.
On July 10, 2001, McGuinness defeated Dean Jablonski in a singles match with the HWA Tag Team Championships on the line (the co-holder of the titles, Chet Jablonski, was indisposed), claiming the titles for himself and his partner, The Human Time Bomb. McGuinness and The Bomb held the titles until August 7, when the Jablonski brothers regained the titles. McGuinness and The Bomb would become champions for a second time on July 23, 2002, defeating the Jablonski brothers once more. They lost the titles to Southern Breeze later that year.
In 2003 McGuinness introduced the HWA European Championship to HWA. He held the title until September 30, 2003, when he lost to Hoss. He regained the title on November 4 and promptly retired it.
McGuinness won the HWA Heavyweight Championship on September 6, 2003 in Batavia, Ohio, defeating Chad Collyer, He held the title until January 3, 2004, when he lost the title to Hoss. McGuinness defeated Hoss to begin a second heavyweight title reign on January 6, and held the title until March 17, 2004, when he lost to El Temor.
McGuinness regularly carries an iron (decorated with the Union Jack) to ringside. When asked, the typical story given is that a group of men once broke into his home to attack him, but he was able to defend himself with the iron. In reality, he began carrying the iron after a girlfriend's mother asked him why some wrestlers carried weapons to ringside, and then enquired as to whether anyone had ever carried an iron before.
On March 5, 2006, McGuinness became the longest reigning ROH Pure Champion in history, surpassing John Walters' previous record of 189 days.