On February 12, 2021, Hayes signed a contract with WWE and was assigned to the WWE Performance Center. He would make his in-ring debut on the June 1 episode of NXT, where he accepted Kushida's open challenge for the NXT Cruiserweight Championship, but was defeated. On the June 22 episode of NXT, Hayes had his second match on television, confronting and then facing Adam Cole in a losing effort. On July 6, Hayes was announced to be apart of the 2021 NXT Breakout Tournament. On the July 27 episode of NXT, Hayes defeated Josh Briggs in the first round. On the August 24 episode of NXT, Hayes defeated Odyssey Jones to win the 2021 NXT Breakout Tournament. On the September 14 episode of NXT, Hayes and a debuting Trick Williams maliciously attacked Duke Hudson before his match, turning heel in the process.
On October 12 episode of NXT 2.0, Hayes successfully cashed in his Breakout Tournament contract on Isaiah "Swerve" Scott to win the NXT North American Championship. Hayes successfully defended his title against Johnny Gargano and Pete Dunne in a triple threat match on the November 23 episode. On January 4, 2022, at the special New Year's Evil episode of NXT 2.0, Hayes defeated NXT Cruiserweight Champion Roderick Strong to unify the North American Championship and Cruiserweight Championship. The Cruiserweight Championship was immediately retired, with Hayes recognized as the final Cruiserweight Champion and continuing as North American Champion. He successfully retained his championship against Cameron Grimes at the Vengeance Day special episode on February 15, 2022. On the March 1 edition of NXT, Hayes retained title against Pete Dunne. He would lose the title on April 2, at NXT Stand and Deliver, in a fatal five-way ladder match involving Santos Escobar, Solo Sikoa, Grayson Waller, and Cameron Grimes, who won the title. Hayes would get his rematch in a triple threat match at NXT Spring Breakin' against Cameron Grimes and Solo Sikoa in a losing effort. At NXT In Your House, Hayes defeated Cameron Grimes to regain the North American Championship. On the September 13 episode of NXT, Hayes was defeated by Solo Sikoa, losing the championship and ending his second reign at 101 days. After Sikoa was stripped of the title the following week, Hayes was announced as the first of five men to compete in a ladder match for the vacant title at Halloween Havoc. At the event on October 22, Hayes failed to regain the championship as the match was won by Wes Lee. Hayes competed in the inaugural Iron Survivor Challenge at NXT Deadline on December 10, which was won by Grayson Waller. Following this, Hayes would begin a feud with Apollo Crews, where they would trade victories with each other, leading to a two-out-of-three falls match at NXT Vengeance Day, where Hayes defeated Crews in two straight falls. Later that night, Hayes and Williams confronted NXT Champion Bron Breakker following the latter's victory over Grayson Waller, teasing a future match between the two.
After weeks of teasing, the match between Hayes and Breakker for the NXT Championship was confirmed for NXT Stand & Deliver. With an assist from Trick Williams, Hayes defeated Breakker on April 1 to win the NXT Championship in the main event. During the build up to the match, Hayes would begin to slowly turn face. Hayes' face turn was solidified on the April 4 episode of NXT, after he was attacked by Breakker after a show of respect, turning Breakker heel. At NXT Battleground on May 28, Hayes successfully defended the NXT Championship against Breakker. On May 30 episode of NXT, Hayes successfully defended the NXT Championship against Noam Dar, when he was attacked by Baron Corbin. Hayes made his main roster debut on the June 27 episode of Raw, where he lost a non-title match against Finn Bálor. On June 27 at Gold Rush, Hayes successfully defended the NXT Championship against Baron Corbin. At the Great American Bash on July 30, Hayes successfully defended the title against Ilja Dragunov. On the following episode of NXT, Williams told Hayes that he needed to leave and shine on his own, breaking up the duo. At NXT No Mercy on September 30, Hayes lost the NXT Championship to Dragunov, ending his reign at 182 days. Earlier that night, Williams defeated "Dirty" Dominik Mysterio to become the new NXT North American Champion.
On the October 17 episode of NXT, Williams was slotted into the triple threat match between Hayes, Dijak and Baron Corbin to make it a fatal four-way match for an NXT Championship opportunity against Dragunov at NXT Halloween Havoc. This announcement caused a rift between Hayes and Williams. Before the match started, Williams was found attacked backstage and had to be taken to a hospital; Hayes went on to defeat Dijak and Corbin for the title opportunity. On night two of Halloween Havoc, Williams returned during the NXT Championship match and cost Hayes the title, with Williams staring Hayes down after the match. On the November 21 episode of NXT, Hayes lost to Josh Briggs to qualify for the Iron Suvivor Challenge at NXT Deadline after interference from Lexis King. This led to a match made between Hayes and King at NXT Deadline, which Hayes won. After the match, King said that he did not attack Williams back in October and thanked Hayes for the premium live event spotlight. The following day, NXT head Shawn Michaels announced that Hayes would represent NXT in SmackDown's United States Championship number one contender tournament. On the December 12 episode of NXT, Hayes accused Ilja Dragunov of attacking Williams in October and himself early that night, which Dragunov denied. In his SmackDown debut on December 15, Hayes defeated Grayson Waller to advance in the United States Championship tournament. However, Hayes would lose to Kevin Owens in the second round on the December 22 episode of SmackDown.
On the January 17, 2024 episode of NXT, Hayes and Williams defeated Edris Enofé and Malik Blade in the first round of the Dusty Rhodes Tag Team Classic. On the January 26 episode of SmackDown, Hayes lost to Austin Theory in a rematch from the previous week that ended in a no-contest after both competitors landed on their head from the top rope. After the match, Hayes was beaten down by Theory and Grayson Waller and was saved by Williams. Hayes made his Royal Rumble match debut at the titular event one day later as the fifth entrant. Hayes would eliminate Waller before being eliminated by Finn Bálor. On the January 30 episode of NXT, Hayes and Williams defeated Latino World Order's Joaquin Wilde and Cruz Del Toro to advance to the finals of the Dusty Rhodes Tag Team Classic. At NXT Vengeance Day on February 4, Hayes and Williams failed to win the Dusty Rhodes Tag Team Classic, which was won by Baron Corbin and Bron Breakker. Later that night, after Williams failed to win the NXT Championship from Ilja Dragunov, Hayes attacked Williams with a steel chair, ending their partnership and turning heel in the process. On the following episode of NXT, Hayes revealed that he was the one who attacked Williams back in October 2023. At NXT Roadblock on March 5, Hayes was defeated by The Family's Tony D'Angelo to determine the number one contender to the NXT Championship at NXT Stand and Deliver after D'Angelo distracted Hayes using Williams' entrance music. After the match, Hayes was attacked by a returning Williams in the ring. The following week on NXT, Williams challenged Hayes to a match at NXT Stand and Deliver, which was made official a few days later. Hayes was defeated by Williams at the event on April 6. In a rematch on the April 16 episode of NXT, Hayes lost to Williams in a steel cage match in his final match for NXT.
On night one of the 2024 WWE Draft on the April 26 episode of SmackDown, Hayes was drafted to the SmackDown brand as the third overall draft pick. He then challenged Undisputed WWE Champion Cody Rhodes to a match as his first opponent as a main roster wrestler, which he lost. Hayes next entered the 2024 King of the Ring tournament, where he defeated Baron Corbin in the first round but lost to Randy Orton in the quarterfinals. In June, Hayes qualified for the men's Money in the Bank ladder match by defeating Orton and The Bloodline's Tama Tonga in a triple threat match. At Money in the Bank on July 6, Hayes lost the ladder match after Drew McIntyre grabbed the Money in the Bank briefcase. On the July 17 episode of Speed, Hayes and Ilja Dragunov fought to the first time limit draw in their Speed Championship number one contender's tournament semifinal match. It was decided that both men were eliminated from the tournament and the winner of the other semifinal, Baron Corbin, would receive a bye to the tournament final to face Speed Champion Andrade for the title.
Following Money in the Bank, Hayes began a feud with Andrade. On the August 9 of SmackDown, Hayes assisted Legado del Fantasma's Santos Escobar to defeat Andrade in a United States Championship number one contender's match. The following week, Hayes successfully defeated Andrade after suffering two losses against him. By the end of September, Hayes and Andrade had won three matches each against each other. On the October 4 episode of SmackDown, Hayes defeated AJ Styles by referee stoppage to earn a United States Championship match against LA Knight, but failed to win the title the following week. On the October 25 episode of SmackDown, Hayes' and Andrade's game seven match, which was also for a United States Championship opportunity, ended in a no-contest after special guest referee LA Knight took both men out, ending their best-of-seven series match at three wins, three losses and a draw each. After the match, SmackDown General Manager Nick Aldis announced that Knight would defend his title against Hayes and Andrade in a triple threat match at Crown Jewel, which Knight would go on to win. On the December 13 episode of SmackDown, Hayes started a rivalry with Braun Strowman after Strowman was selected as Hayes' surprise opponent, where he lost the match. On the December 20 episode of SmackDown, Hayes interrupted Strowman's interview on The Grayson Waller Effect with A-Town Down Under (Grayson Waller and Austin Theory), which later culminated in a match between Strowman and Hayes, with Hayes winning via count-out.
On the January 17, 2025 episode of SmackDown, Hayes began a feud with Jimmy Uso after challenging him to a match, which ended in a disqualification after The Bloodline's Tama Tonga and Jacob Fatu attacked Jimmy. Following the beatdown, Hayes would then try to form an alliance with The Bloodline, but would end up getting attacked by Fatu. Hayes would then face Damian Priest, who moved from Raw, one week later but was unsuccessful. On the January 31 episode of SmackDown, Hayes had a rematch against Jimmy Uso but was unsuccessful. At the Royal Rumble on February 2, Hayes entered the titular match at number four, but was eliminated by Bron Breakker. Afterwards, Hayes attacked Akira Tozawa, causing him to be replaced in the Royal Rumble by celebrity entrant IShowSpeed. On the February 14 episode of SmackDown, Hayes faced R-Truth following a backstage confrontation between the two, and was victorious. On the February 21 episode of SmackDown, Hayes formed a partnership with The Miz as Melo Don't Miz, where they defeated R-Truth and LA Knight in their first match together. On the April 18 episode of SmackDown, Hayes won the André the Giant Memorial Battle Royal, last eliminating Andrade. On September 16, at NXT Homecoming, Hayes and Trick Williams reunited for one-night only, defeating DIY (Johnny Gargano and Tommaso Ciampa) with the help of The Miz. On the September 26 episode of SmackDown, during a tag team match against The Street Profits (Angelo Dawkins and Montez Ford) and after The Miz tried to take the glory and tag himself in, Hayes cut him off, causing them to lose the match. The following week on SmackDown, Hayes was attacked by The Miz as he was about to accept United States Champion Sami Zayn's open challenge for the title, disbanding Melo Don't Miz. On the December 26 episode of SmackDown, Hayes defeated United States Champion Ilja Dragunov in an open challenge to win his first title on the main roster.