He and Gillberg (as the Lords) began appearing on WWF television, although used as preliminary wrestlers, he and Gillberg had matches on WWF Primetime Wrestling against the Legion of Doom (Hawk and Animal), The Orient Express, The Rockers (Marty Jannetty and Shawn Michaels) and "Hacksaw" Jim Duggan and Sgt. Slaughter between 1990 to late 1991. On June 5, 1990, he and Gill faced WWF Tag Team Champions Demolition at the War Memorial Auditorium in Rochester, New York. They also faced Rhythm and Blues (The Honky Tonk Man and Greg Valentine) in Hershey, Pennsylvania on August 28. As well as teaming with Gillberg, Hardy occasionally teamed with different partners such as with Paul Perez against WWF World Tag Team Champions The Hart Foundation (Bret Hart and Jim Neidhart) and with Ross Lindsay against Power and Glory (Hercules and Paul Roma).
In the WWF that year, he also wrestled "Texas Tornado" Kerry Von Erich, Big Bully Busick and WWF Million Dollar Champion Virgil.
During mid-1992, he faced Bret Hart, Crush, Bob Backlund and Lance Cassidy. During his matches with Backlund and Cassidy, Doink played practical jokes on his opponents after the match setting up Backlund to slip on a banana peel and putting a "kick me" sign on Cassidy's ring jacket. When Cassidy put the jacket back on after the match, Doink kicked him. Hardy later appeared in single matches against Tatanka and "British Bulldog" Davey Boy Smith on WWF Superstars and teamed with Kato of the Orient Express losing to The Bushwhackers on May 5, 1992.
He and Gillberg also participated in two of three 40-man battle royals held that year. The first, on June 2, included Money Inc. (Ted DiBiase and IRS), The Nasty Boys (Brian Knobs and Jerry Saggs), The Beverly Brothers (Beau and Blake Beverly) and High Energy (Koko B. Ware and Owen Hart) as well as Sgt. Slaughter, Bret Hart, British Bulldog, Virgil, Tito Santana, Rick Martel, "The Texas Tornado" Kerry Von Erich, Skinner, Repo Man, Jim Powers, Jim Brunzell, Glenn Ruth, Phil Apollo, Barry Horowitz, Bobby Star, Dublin Destroyer, Rick Johnson, Al Hunter, Bob Knight, Rick Danger, Jerry Davis, Scott Antonio, Tony Ulysses, Bruce Mitchell, Joe Milano and several others. The battle royal was later featured on WWF Rampage '92.
The second battle royal took place two months later. He and Gillberg (as The Executioners) took part in a 40-man battle royal won by Tatanka and which included Tito Santana, Bret Hart, Sgt. Slaughter, Col. Mustafa, Shawn Michaels, Crush, Kerry Von Erich, Virgil, Skinner, Repo Man, Barry Horowitz, Jim Powers, Brooklyn Brawler, Reno Riggins, Dale Wolfe, Brian Costello, Chuck Casey, Dom Jones, Burt Spears, Thor Anderson, Tom Cumberland, Mark Kordis, Legion of Doom, Money Inc. (Ted DiBiase and IRS), The Beverly Brothers (Beau and Blake Beverly), The Nasty Boys (Brian Knobs and Jerry Saggs), High Energy (Koko B. Ware and Owen Hart) and The Natural Disasters (Earthquake and Typhoon). The battle royal was the first and largest held in WWF history and was later profiled in WWF Magazine.
He made his last WWF appearances on WWF Primetime losing to Davey Boy Smith on September 28 and Bret Hart on October 5, 1992.
He and Gillberg would begin wrestling in the World Wrestling Federation as The Executioners in early 1993. On March 9, only three days after losing their tag team titles, he and Gill also made an appearance as Toxic Turtles at the sold-out Augusta Civic Center with 8,000 in attendance. Their match was later taped for WWF Challenge. In singles matches, Hardy faced Tito Santana in his last WWF television appearance and was pinned by Santana in Wilkes Barre, Pennsylvania on July 6, 1993. He wrestled against Tatanka, Jim Duggan, Virgil, Mr. Perfect, and Razor Ramon as well as teaming with Reno Riggins, the Brooklyn Brawler, Bert Centeno and Barry Horowitz.
Appearing on Monday Night Raw throughout the year, he and Gillberg would face The Steiner Brothers (Rick and Scott Steiner), The Quebecers (Jacques and Pierre) and Men on a Mission (Mo and Mabel). They had previously faced Men on a Mission in their WWF debut on WWF Challenge several months before splitting up with Gillberg in 1995.
Hardy himself soon left the WWF after losing to The Steiner Brothers in a tag team match with Mike Khoury on April 18, 1994.
Hardy returned to the WWF for a short time facing The Bushwhackers, The Headshrinkers (Samu and Fatu) and The Smoking Gunns (Bart and Billy Gunn) with various tag team partners before leaving in 1995. During this time, he also wrestled single matches against Davey Boy Smith and Jim Neidhart.