On March 17, 2013, Murphy signed a development contract with WWE. He reported to NXT and debuted at an NXT house show on November 23, 2013, teaming with Sawyer Fulton and Troy McClain against Colin Cassady, Angelo Dawkins and Wesley Blake. On the May 15, 2014 episode of NXT, he teamed with Elias Samson in a losing effort against The Ascension.
In August 2014, Murphy formed a tag team with Wesley Blake. On 14 August episode of NXT, they were defeated in the first round of a number one contender tag team tournament by The Lucha Dragons (Kalisto and Sin Cara). For the rest of 2014, they lost multiple matches to The Lucha Dragons and The Vaudevillains (Aiden English and Simon Gotch). Also in October 2014, they lost a number one contender tag team battle royal, being eliminated by The Ascension.
On 21 January 2015 episode of NXT, Blake and Murphy defeated The Vaudevillains and quickly challenged The Lucha Dragons to a title match. On 28 January episode of NXT, Blake and Murphy defeated the champions to win the NXT Tag Team Championship, making Murphy the first Australian to hold a championship in WWE. At NXT TakeOver: Rival, Blake and Murphy, now billed simply by their surnames, defeated the Lucha Dragons in a rematch for the title. Following that in March, Blake and Murphy began a feud with Enzo Amore and Colin Cassady, who were intent on capturing the tag titles. Blake and Murphy attempted to woo Carmella on several occasions. On 13 May episode of NXT, Blake and Murphy distracted Carmella during her match with Alexa Bliss, causing her to lose which established them as heels in the process. At NXT TakeOver: Unstoppable, during Amore and Cassady's NXT Tag Team Championship match against Blake and Murphy, Alexa Bliss came out mid-match and attacked Carmella and Amore, ensuring the win for Blake and Murphy. After making several successful title defenses, Blake and Murphy lost the championships to the Vaudevillians at NXT TakeOver: Brooklyn, ending their reign at 219 days. On the 18 May 2016 episode of NXT, after losing to Austin Aries and Shinsuke Nakamura, Bliss and then Blake walked away from Murphy, teasing a split for the team.
An attempt was made by Blake and Murphy to reconcile their differences in a match against TM61 (Nick Miller and Shane Thorne), however miscommunication between the two resulted in defeat. Murphy announced himself as a singles competitor once again when interrupting a meeting between NXT General Manager William Regal and Shinsuke Nakamura on the 22 June episode of NXT, leading to a match with Nakamura in the main event which Murphy lost. Murphy and Blake faced off in a singles match on the 12 October episode of NXT, which ended in a no contest after Samoa Joe interfered and attacked both men. On the 4 January 2017 episode of NXT, Murphy teamed with Tye Dillinger to defeat Bobby Roode and Elias Samson in his hometown of Melbourne, Australia. This was his only televised match of 2017, although he continued to appear at NXT live events.
In early 2018, Murphy lost about 25 pounds and asked to be included in 205 Live brand. On the 20 February episode of 205 Live, he made his debut as a participant in the Cruiserweight Championship tournament, defeating Ariya Daivari in the first round but lost to Mustafa Ali in the quarterfinals. On the 27 March episode of 205 Live, Murphy defeated TJP, Akira Tozawa, and Kalisto in a fatal four-way match for a future shot at the Cruiserweight Championship. On the April 10 episode of 205 Live, Murphy attacked new WWE Cruiserweight Champion Cedric Alexander from behind, starting a feud between the two. However, Murphy failed his mandatory weigh-in and was removed from the match and the 205 Live roster until he met the weight requirement. On the May 8 episode of 205 Live, Murphy defeated Ali in a rematch from their Cruiserweight Championship tournament quarterfinal match.
He started a storyline where he had to lose weight, challenging Alexander for the title on the May 29 episode of 205 Live, where he failed to win the belt. The following week, he had a match with Mustafa Ali that ended in a no-contest after both men were attacked by Hideo Itami, who won a triple threat match against both men the following week. On the July 3 episode of 205 Live, he lost to Ali in a No Disqualification match. He then went on to form a heel tag team with Tony Nese and they would subsequently feud with Lucha House Party (Gran Metalik, Lince Dorado and Kalisto). On October 6 at Super Show-Down in his hometown of Melbourne, Australia, Murphy defeated Alexander to win the Cruiserweight Championship, his first singles title in WWE, and the first Australian man to accomplish this feat. Murphy subsequently retained the title against Mustafa Ali at Survivor Series and Alexander at TLC, respectively.
On 27 January, 2019, Murphy successfully defended his title in a fatal four-way match against Akira Tozawa, Kalisto and Hideo Itami on the Royal Rumble Kickoff Show after pinning Itami. On 17 February, Murphy retained his title against Tozawa at Elimination Chamber. On the WrestleMania 35 Kickoff Show, he lost his title to former partner Tony Nese, ending his reign at 183 days. Prior to this loss, Murphy had been undefeated in televised singles matches dating back to July 2018. On the 9 April episode of 205 Live, Murphy was again defeated by Nese in a rematch for the WWE Cruiserweight Championship.
On the 16 April edition of SmackDown, it was announced that Murphy would be drafted the SmackDown brand as part of the 2019 WWE Superstar Shake-Up. He participated in the 51-Man Battle Royal at WWE Super Showdown in June but was unsuccessful. In August, Murphy became heavily involved in a storyline with Roman Reigns, who was attempting to discover his mystery attacker. After being confronted by Reigns on the August 6 episode of SmackDown, Murphy would reveal that Rowan was Reigns' alleged attacker. At SummerSlam Murphy defeated Apollo Crews by disqualification after Rowan attacked him mid-match. Two days later on SmackDown Live, Murphy would have his in-ring television debut in a losing effort to Roman Reigns. The following week, Murphy defeated Daniel Bryan in an upset victory. Murphy would then participate in the King of the Ring tournament where he lost to Ali in the first round. After the match, the two shook hands.
As part of the 2019 WWE Draft, Murphy was drafted to the Raw brand. He made his debut on that same night (October 14), in a winning effort against Cedric Alexander. Over the following weeks, Murphy would develop a winning streak defeating the likes of Matt Hardy, Akira Tozawa and Zack Ryder. On the November 19 episode of Raw, Murphy began a feud with Aleister Black after he knocked on Black's door and called him a coward. The following week, Murphy was confronted by Black where the two proceeded to brawl setting up a match at WWE TLC. At the event, Murphy was defeated by Black. He then lost to Black again on the December 30 episode of Raw, and once again on the January 13, 2020 episode of Raw to end the feud.
Later on in the night of the January 13, episode of Raw, Murphy sat at the barricade, dejected after his third loss. After getting requested for help by Seth Rollins, Murphy would assist Rollins and the AOP (Akam and Rezar) in their Fist Fight main event against Kevin Owens, Samoa Joe, and Big Show, therefore aligning himself with the faction as their new member. The following week on Raw, Murphy and Rollins defeated The Viking Raiders (Erik and Ivar) to win the WWE Raw Tag Team Championship. On 7 February, his ring name was shortened back to simply Murphy. Murphy and Rollins successfully defended the tag titles against The Street Profits (Angelo Dawkins and Montez Ford) at Super ShowDown on 27 February, but lost the titles to them on 2 March episode of Raw, ending their reign at 42 days. Murphy and Rollins failed to reclaim the championship from the team at Elimination Chamber six days later.
On the April 20 episode of Raw, Murphy lost to Rey Mysterio in a Money in the Bank ladder match qualifier. The following week, Murphy saved Rollins' from an attack by Drew McIntyre. However, McIntyre laid him out with a Claymore. The two had a match were McIntyre defeated Murphy. Some weeks later on Raw, Rollins savagely attacked Rey Mysterio in a tag team match, where he and Aleister Black battled Rollins and Murphy, and won by disqualification when Rollins pulled Mysterio off of the ring apron. In the midst of the post-match assault, Mysterio's eye was severely injured in storyline when Rollins forced his face onto the steel steps. After this event, Murphy restarted his rivalry with Black. On the July 27 episode of Raw, Murphy and Rollins injured Black's right eye by driving it through the steel steps. Murphy and Rollins continued feuding with Mysterio, which also saw the involvement of Mysterio's son Dominik Mysterio. At Payback, Rollins and Murphy were defeated Rey and Dominik after Murphy accidentally kicked Rollins, costing them the match. This would cause tension between Rollins and Murphy as Rollins began berating Murphy telling him to stay backstage and not get involved in his matches. However, on the September 14 episode of Raw, after Murphy interfered during a steel cage match between Dominik and Rollins and accidentally slammed the door against Rollins, Rollins would viciously attack Murphy. Murphy would then begin a storyline with Mysterio's daughter Aalyah after he apologized to her for Rollins' actions towards her family, leading her to believe that Murphy was not as bad as Rollins. On the October 5 episode of Raw, Murphy attacked Rollins after he refused to apologize to him, thus appearing to turn face for the first time in his WWE career. After Murphy would force Rollins to apologize to Aalyah and the Mysterio family, Rollins would assault Murphy with a kendo stick until Aalyah intervened.
As part of the 2020 draft in October, Murphy was drafted to the SmackDown brand. On the October 30 episode of SmackDown, Aalyah kissed Murphy in front of her father and brother while Rollins observed from the stage, thus confirming their status as a couple. He cemented his face turn by costing Rollins a No Holds Barred match against Mysterio on the November 13 episode of SmackDown and shaking hands with Rey and Dominik afterwards. On the November 20 episode of SmackDown, Murphy defeated Rollins to end the feud. The love storyline between Murphy and Aalyah would be dropped shortly after and Murphy would be taken off television.
Murphy returned on March 5, 2021 episode of SmackDown, offering to help Rollins against Cesaro, to which Rollins rebuffed, and Murphy would then go on to lose in a match against Cesaro. On June 2, 2021, Murphy was released by WWE.