On December 15, 2016, it was revealed that Dunne would be one of sixteen men competing in the two-night United Kingdom Championship Tournament to crown the first ever WWE United Kingdom Champion on January 14 and 15, 2017. Dunne defeated Roy Johnson in the first round, advancing to the quarter finals and eventually the semi-finals where he defeated Sam Gradwell and Mark Andrews respectively to advance to the finals, where he lost to Tyler Bate. Dunne then signed a contract with WWE. He then became a part of NXT, making his debut on February 22, 2017 in a winning effort against Mark Andrews. On April 4, Dunne, and others who participated in the tournament, appeared on 205 Live to promote upcoming UK live shows.
On May 7, Dunne defeated Trent Seven at a live event to become the new number one contender for the United Kingdom Championship. Dunne then went on to defeat Bate at NXT TakeOver: Chicago to win the title for the first time in a highly acclaimed match, which was later named Match of the Year at the NXT Year-End Awards. Dunne made his main roster debut during a one-off appearance on the 6 November episode of Raw in Manchester, England, where he defeated WWE Cruiserweight Champion Enzo Amore in a non-title champion versus champion match. He then kept on defending his title on NXT, first against Bate on December 20, and then against Roderick Strong on February 14, 2018.
Dunne turned face when he and Strong subsequently teamed up, starting on March 28 for the Dusty Rhodes Tag Team Classic, defeating Danny Burch and Oney Lorcan in the first round and Alexander Wolfe and Eric Young of SAnitY in the semi-finals. They faced The Authors of Pain in the finals on March 4; however, the match ended in a no contest when Kyle O'Reilly and Adam Cole of The Undisputed Era attacked both teams.
As the result, all three teams faced each other in a triple threat tag team match at NXT TakeOver: New Orleans, which acted as the final match of the tournament while The Undisputed Era's NXT Tag Team Championship was also on the line. At the event, Strong turned on Dunne and attacked him, giving the victory to The Undisputed Era and aligning himself with the stable. This would mark the beginning of a feud between Dunne and The Undisputed Era, starting with a singles match on the May 2 episode of NXT, in which he defeated Strong by disqualification after being attacked by Cole and O'Reilly.
At the 2018 United Kingdom Championship Tournament event, Dunne teamed up with Tyler Bate and Trent Seven as British Strong Style on the first night to defeat The Undisputed Era, and on the second night, retained his title against United Kingdom Championship Tournament winner Zack Gibson. In July, the NXT UK brand was established, with the United Kingdom Championship as its top title; Dunne subsequently defended the title on both brands. On the 22 August episode of NXT (which also served as the pre-show of NXT TakeOver: Brooklyn 4), Dunne once again retained his championship against Gibson; in parallel, he became the longest-reigning champion in WWE at (then) 456 days following Brock Lesnar's loss of the WWE Universal Championship at SummerSlam.
On the August 29 episode of NXT, Dunne teamed up with NXT North American Champion Ricochet against The Undisputed Era, losing due to a miscommunication. As both blamed the other for their loss, the two had a match for both titles on the September 19 episode of NXT, marking the first time a WWE United Kingdom Champion faced a NXT North American Champion. The match ended in a no contest after The Undisputed Era attacked both men. After numerous attacks in the following weeks, Dunne eventually teamed up with Ricochet and the War Raiders to take on Undisputed Era at NXT TakeOver: WarGames in the titular match, where his team would pick up the victory.
At NXT UK TakeOver: Blackpool on 12 January 2019, the inaugural NXT UK TakeOver event, Dunne retained his title against Joe Coffey in the main event. Two weeks later, Dunne appeared as a surprise entrant in the Royal Rumble match at the namesake pay-per-view on 27 January. He would fail to win however, as he was eliminated by Drew McIntyre. At NXT TakeOver: New York, Dunne lost the UK Championship to Walter, ending his record setting reign at 685 days.
On the April 14 episode of NXT UK (aired May 22), Dunne lost his rematch against Walter for the United Kingdom Championship, after interference by Fabian Aichner and Marcel Barthel, thus turning Walter heel. The following week, after Walter, Aichner and Barthel declared the formation of Imperium, Dunne, with British Strong Style, brawled with them in the ring.
Dunne returned to regular NXT in June 2019, rekindling his feud with Roderick Strong; after Strong started a feud of his own with NXT North American Champion Velveteen Dream, Dunne got involved on the July 24 episode of NXT, attacking Strong and indicating his desire to go after Dream's title. The three faced off in a triple threat match for the title at NXT TakeOver: Toronto, where Velveteen Dream retained his title. On the October 2, episode of NXT, Dunne would begin a feud with Damian Priest when he was attacked by him after winning a match against Danny Burch. From there, on the October 16 episode, before his match with Priest, Dunne would get into an argument with Killian Dain after his match with Boa. He proceeded to snap Dain’s fingers as he walked into the ring, while officials try to separate the two. Dunne would go on to lose to Priest as he was hit by a low blow by him. He would then face Priest and Dain in a triple threat match at NXT TakeOver: WarGames, which he won, and would go on the next night at Survivor Series to face Adam Cole for the NXT Championship, which ended in a losing effort.
On the January 10, 2020 episode of NXT, the participants of the 2020 Dusty Rhodes Tag Team Classic were announced, with Dunne and Matt Riddle being announced as surprise participants; they would later take on the name of The Broserweights, a portmanteau of Dunne's "Bruiserweight" nickname and Riddle's "Original Bro" nickname. Together, they deafeated Mark Andrews and Flash Morgan Webster in the first round on January 15, Fabian Aichner and Marcel Barthel of Imperium in the semifinals on January 22, and Grizzled Young Veterans (James Drake and Zack Gibson) in the finals on January 29 to win the tournament and earn a match against Bobby Fish and Kyle O'Reilly of The Undisputed Era for the NXT Tag Team Championship at NXT TakeOver: Portland. At the event on February 16, Dunne and Riddle defeated Fish and O'Reilly to win the titles. When Dunne was unable to compete, Timothy Thatcher substituted him. Riddle and Thatcher would lose the titles against Imperium (Fabian Aichner and Marcel Barthel) on May 13, 2020.
Dunne remained inactive from March to October 2020; meanwhile, Riddle moved to the SmackDown brand, resuming his activities as a singles wrestler. Dunne eventually made his return on the NXT UK brand on October 15, 2020, teaming up with Ilja Dragunov to defeat NXT UK Champion Walter and Alexander Wolfe of Imperium.
On October 28 at NXT Halloween Havoc, Dunne returned to NXT and turned heel for the first time since 2018 by attacking Kyle O'Reilly and aligning himself with Pat McAfee, Danny Burch and Oney Lorcan. They faced pff against Undisputed Era at NXT Takeover: WarGames, where Dunne was the first competitor from Team McAfee to enter the match along with O’Reilly. Team McAfee lost the match when O’Reilly pinned Burch. Dunne then faced the NXT Champion Finn Bálor at NXT TakeOver: Vengeance Day for Bálor’s NXT Championship in a losing effort. Dunne would then enter a feud with Kushida, which would come to a head at NXT TakeOver: Stand and Deliver. At the event, Dunne would defeat Kushida.
On the July 27 NXT, Ridge Holland returned from injury by attacking Tommaso Ciampa and Timothy Thatcher after Dunne and Lorcan's match against the latter, thus joining their alliance. Dunne turned face when he stomped the fingers of Tony D'Angelo and joined Team Black and Gold, consisting of Ciampa, Johnny Gargano and LA Knight for NXT WarGames. At the event, his team lost to Team 2.0 (D'Angelo, Grayson Waller, Carmelo Hayes, and Bron Breakker) in the titular WarGames match. After WarGames, Dunne remained face and continued feuding with D'Angelo. On the December 21 episode of NXT 2.0, Dunne defeated D'Angelo in singles competition but, after the match, was brutally attacked by D'Angelo with a crowbar. The two would face on in a Crowbar on a Pole match on the January 11, 2022 episode, with D'Angelo defeating Dunne. The feud would culminate at NXT Vengeance Day, where Dunne defeated D'Angelo in a weaponized steel cage match.
On the March 11 episode of SmackDown, Dunne made his official main roster debut under the new ring name Butch and aligned himself with Ridge Holland and Sheamus in their feud against Big E and Kofi Kingston. On the April 8 episode of SmackDown, Butch competed in his first match on the brand, where he was defeated by Xavier Woods. At Clash of the Castle, Butch managed Sheamus against Gunther in an Intercontinental Championship match. Though Sheamus was unsuccessful, he received a standing ovation from the Cardiff crowd, effectively turning Butch—and the Brawling Brutes—face in the process. On the September 16 episode of SmackDown, he and Ridge won a fatal four-way tag team match to become the number one contenders for the Undisputed WWE Tag Team Championships. The following week, they faced the champions The Usos for the titles in a losing effort, after interference from Imperium. They had another opportunity at Crown Jewel on November 5, but lost again. Butch would later enter a feud with The Bloodline with help from his stablemates, Kevin Owens and Drew McIntyre. This would culminate at Survivor Series WarGames on November 26 in a WarGames match, in which they lost.
On the June 9 episode of SmackDown, Butch defeated Baron Corbin to qualify for the men's Money in the Bank ladder match. However, Damian Priest would win the match at the namesake event. Later in the year, Butch would be invited to the NXT Global Heritage Invitational on NXT. He would be put in Group A alongside Tyler Bate, Axiom, and Charlie Dempsey. Butch would lead in the grouping and face the winner of Group B, Joe Coffey; Butch would win the match against Coffey to become the number one contender for Noam Dar's NXT Heritage Cup at No Mercy. At the event, Butch would be unsuccessful in winning the Heritage Cup. On the November 17 episode of SmackDown, visible dissension appeared between Holland and Butch after a loss to the Street Profits. One week later, Holland walked out on Butch during a tag team match against Pretty Deadly, resulting in a loss for what would be their final match as a team.
Butch soon reunited with Tyler Bate, who was promoted to SmackDown on January 5, 2024 at SmackDown New Year's Revolution, to reform British Strong Style. On the January 19 episode of SmackDown, Butch returned to his original ring name, Pete Dunne, and defeated Pretty Deadly in a rematch from SmackDown: New Year's Revolution. On the February 23 episode of SmackDown, the duo of Bate and Dunne was renamed to New Catch Republic. New Catch Republic won an Undisputed WWE Tag Team Championship contender series for an Undisputed WWE Tag Team Championship match at Elimination Chamber: Perth, but failed to defeat The Judgment Day (Finn Bálor and Damian Priest) for the titles at the event. New Catch Republic participated in a six-pack tag team ladder match for the Undisputed WWE Tag Team Championships on night one of WrestleMania XL, but failed to win any of the titles.
On night two of the 2024 WWE Draft, New Catch Republic were drafted to the Raw brand in the supplemental draft. In July, Bate was sidelined with a torn pectoral muscle after he suffered an injury, putting the team on hiatus. On the July 8 episode of Raw, Dunne and Sheamus had a mini reunion, where Dunne was saved by Sheamus from a beatdown from Bronson Reed after their match. Sheamus then embraced Dunne, with Dunne shoving Sheamus away. The following week on Raw, Dunne attacked Sheamus from behind and left him to be further attacked by Reed, turning heel for the first time since 2022.