In June 2016, it was reported that Black had signed with WWE. He reported to the WWE Performance Center on 19 October. On November 3, Black appeared on a house show at Ft. Pierce, Florida and cut a promo saying that he came to NXT to "burn" it down. On 11 November, at a house show in St. Augustine, Florida, Black made his in-ring debut, defeating Lince Dorado. On January 15, 2017, Black made a surprise appearance at the WWE UK Championship Tournament finals as Tommy End, losing to Neville in a non-tournament match.
Vignettes began to air from the 8 March episode of NXT promoting Black's television debut at NXT TakeOver: Orlando. At NXT TakeOver: Orlando, Black made his televised in-ring debut as a face, defeating Andrade "Cien" Almas. In May, Black made his main roster debut on WWE Main Event while on the European Tour, defeating Curt Hawkins. On the June 21 edition of NXT, he defeated Kassius Ohno.
On the August 2 edition of NXT, prior to Black's match against the debuting Kyle O'Reilly, Hideo Itami cut a promo in the ring, demanding respect. Black interrupted Itami, resulting in a stand-off between the two. Black performed Black Mass on Itami, and defeated O'Reilly. Itami attempted to attack Black afterwards, but the two were eventually separated. At NXT TakeOver: Brooklyn III, Black defeated Itami. Black began a feud with Velveteen Dream, where Dream constantly stalked and harassed Black in order for him to say his name. This led to a match at NXT TakeOver: WarGames, which Black won. After the match, Black sat next to a dazed Velveteen Dream, before ultimately saying his name.
On the December 13 episode of NXT, Black defeated Adam Cole to qualify for a number one contender's fatal-four way match for the NXT Championship, which also involved Johnny Gargano, Killian Dain and Lars Sullivan on the December 27 episode of NXT, which Gargano won by pinning Black (marking his first pinfall defeat on NXT) after interference from The Undisputed Era. At the NXT Year-End Awards, Black won three awards for Rivalry of the Year (with Velveteen Dream), Breakout Star of the Year, and Male Competitor of the Year.
Black defeated Cole in an Extreme Rules match at NXT TakeOver: Philadelphia. On the February 14, 2018 episode of NXT, he said that he had "a devil on [his] back", which was the NXT Championship. He was then interrupted by Killian Dain, whom he defeated on the March 7 edition of NXT to become the number one contender for the NXT Championship. He received his title opportunity against Andrade "Cien" Almas at NXT TakeOver: New Orleans on April 7, where he won to become the new NXT Champion. On the May 30 episode of NXT, Black was interrupted by Lars Sullivan, who wanted a shot at the NXT Championship. On that same episode, it was revealed that Sullivan would face Black for the NXT Championship at NXT TakeOver: Chicago II, where Black successfully retained his title.
Black lost the NXT Championship to Tommaso Ciampa at the July 18 NXT TV tapings for the July 25 episode after Johnny Gargano interfered and accidentally hit Black with the title belt. The following week, during Ciampa’s address to the NXT Universe, he approached the ring, only for Gargano to run out ahead of him to attack Ciampa, after which he attacked Gargano with a Black Mass before indicating that his NXT Championship loss was Gargano’s fault.
On the August 8 episode of NXT, Black faced Gargano in a singles match, only for Ciampa to interfere. The three would ultimately brawl until NXT General Manager William Regal would appear and turn Black and Ciampa's singles bout for the NXT Championship at NXT TakeOver: Brooklyn 4 into the first-ever triple threat match for the title, involving Gargano. However, after the show, Black was found unconscious by referees and Regal himself in the parking lot outside the arena after being attacked by an unseen and unknown assailant.
It was later reported that Black was sent to a local medical facility, and was announced as being unable to compete, both due to the on-screen incident and Black suffering a legitimate groin injury at an NXT Live event in Las Vegas. After being out of action for two months, Black returned on the October 17 episode of NXT, confronting Nikki Cross, who revealed that Gargano was the one who had attacked him. A match between Black and Gargano was scheduled for NXT TakeOver: WarGames, in which Black was victorious. On January 26, 2019 he competed at NXT TakeOver: Phoenix for the NXT Championship but he was defeated by Tommaso Ciampa. The next night on January 27, 2019, he entered the Men's Royal Rumble match at Number 21, lasting 6:09 before being eliminated by Baron Corbin.
Black made his official main roster debut on the February 18 episode of Raw, defeating Elias. The next night on SmackDown, he defeated Andrade. Over the next few weeks, Black formed a tag team with Ricochet and entered NXT's Dusty Rhodes Tag Team Classic while also earning a Raw Tag Team Championship match at Fastlane. At Fastlane, Black and Ricochet lost in a triple threat match to The Revival and the team of Bobby Roode and Chad Gable. After winning the Dusty Rhodes Tag Team Classic on March 27, 2019, they earned themselves an opportunity to compete for the NXT Tag Team Championship against The War Raiders at NXT TakeOver: New York, which they would subsequently lose.
The next day, Black and Ricochet would compete at WrestleMania 35 in a fatal four-way tag team match for the WWE SmackDown Tag Team Championship against The Usos, Rusev and Shinsuke Nakamura, and The Bar. The Usos would go on to retain their titles in the match. Black and Ricochet were then drafted to Raw in the 2019 WWE Superstar Shake-up. However, on April 22, Black was re-drafted to the SmackDown brand, due to his real-life wife Zelina Vega being drafted there, therefore splitting him from Ricochet.
Black then began appearing in ominous backstage promos in a dark room, awaiting a challenger. His challenge was eventually accepted, with the mystery opponent to be revealed as Cesaro on the July 9 episode of SmackDown, who would then be Black's opponent at Extreme Rules in Black's first singles pay-per-view match since joining the main roster. At the event, Black defeated Cesaro. Two days later on SmackDown Live, Black would face Cesaro in a rematch where he was once again victorious.
As part of the 2019 WWE Draft, Black was drafted from SmackDown to Raw. On the November 19, 2019 episode of Raw, Black began a feud with Buddy Murphy after he called Black a coward. This led to a matchup at TLC, where Black was victorious. At the Royal Rumble pay-per-view on January 26, 2020, Black entered Royal Rumble match at number 28, but was eliminated by Seth Rollins. On the February 24 episode of Raw, Black was attacked by The O.C. (AJ Styles, Luke Gallows, and Karl Anderson) backstage. The next week on Raw, Black faced The O.C. members in separate matches, and suffered his first loss as part of main roster, by AJ Styles. At Elimination Chamber on March 8, Black defeated Styles in a no disqualification match, with interference from The Undertaker. At WrestleMania 36, on night two of the event, Black defeated Bobby Lashley. In the following weeks, he defeated Apollo Crews and Oney Lorcan, as well as Austin Theory in a Money in the Bank qualifying match. At the Money in the Bank pay-per-view, Black failed to retrieve the briefcase after he was thrown off the roof of WWE headquarters by King Corbin.
Following this, Black would feud with Seth Rollins and Murphy after Rollins injured Rey Mysterio's right eye. On the July 27 episode of Raw, Murphy injured Black's right eye by driving it through the steel steps. On the August 24 episode of Raw, Black returned during The Kevin Owens Show, wearing an eye bandage, and attacked Kevin Owens, turning heel for the first time in his WWE career. Later on, he attacked Owens with his Black Mass finishing move before a match against Randy Orton, due to which Owens lost. On the September 14 episode of Raw, he was defeated by Owens. On the October 12 episode of Raw, Black lost to Owens in a no disqualification match. As part of the 2020 draft in October, Black was drafted to the SmackDown brand. However following the draft, Black would disappear from television for several months.
After a six month absence, Black returned on the April 23, 2021 episode of SmackDown in a vignette promoting his return. After several weeks of vignettes, Black returned on the May 21 episode of SmackDown, attacking Big E with the Black Mass, which allowed Apollo Crews to retain the Intercontinental Championship in the main event. However on June 2, 2021, he was released by WWE.