It was announced on February 11, 2019, that Lumis signed a contract with WWE and would start working at the WWE Performance Center. He made his debut at an NXT house show on March 16, losing to Fabian Aichner. After debuting under his real name, his ring name was changed to Dexter Lumis in June. In June, it was announced that Lumis would compete in a tournament named the NXT Breakout Tournament. Lumis lost in the first round of the tournament to Bronson Reed on the July 17 episode of NXT. On the March 25, 2020 episode of NXT, a vignette aired promoting Lumis' return. The following week, he defeated Jake Atlas in his return match. On the April 22 episode of NXT, he assisted Velveteen Dream in defeating the Undisputed Era after his partner Keith Lee was taken out by Damian Priest. On the May 6 episode of NXT, Lumis once again attempted to assist Dream in his NXT Championship match against Adam Cole, but accidentally knocked out the referee, thus costing Dream the match and the title. On the June 3 episode of NXT, Lumis debuted a new artist element of his gimmick as he brought out an art easel and drew a sketch depicting himself driving a car with the Undisputed Era trapped in the rear deck. At NXT TakeOver: In Your House, Lumis would interfere in the Backlot Brawl match between Cole and Dream as he attacked Roderick Strong and Bobby Fish, throwing them in the rear deck of a car and driving off with them. On the following episode of NXT, Lumis faced Cole in a non-title match, but was defeated after interference from Strong and Fish. On the July 1 episode of NXT: The Great American Bash, Lumis defeated Strong in a strap match. On the July 29 episode of NXT, Lumis defeated Timothy Thatcher and Finn Bálor to qualify for an NXT North American Championship opportunity at NXT TakeOver: XXX. However, the following week, it was announced that Lumis suffered an injury and was removed from the match.
Lumis made his return on the September 30 episode of NXT, appearing in a backstage segment with Cameron Grimes. He defeated Austin Theory the following week but was attacked by Grimes after the match. On the October 14 episode of NXT, Lumis challenged Damian Priest for the NXT North American Championship, but lost after Grimes came out and stomped him on the apron while the referee was checking on Priest. Lumis went on to defeat Grimes in a Haunted House of Terror match at NXT Halloween Havoc. On the November 11 episode of NXT, Lumis faced Timothy Thatcher in a match after the latter threw August Grey into a caricature that was painted by Lumis backstage. Lumis would lose that match after Grimes interfered again with a distraction. Grimes subsequently wrapped Lumis's head in a burlap sack and attacked him. The following week, they faced off in a blindfold match, which ended in an apparent no contest after Grimes unknowingly knocked the referee unconscious and eventually ran off. Lumis then defeated Grimes in a strap match on December 6 at NXT TakeOver: WarGames. On January 6, 2021, he hosted NXT: New Year's Evil. On the January 13 episode of NXT, Lumis lost to Johnny Gargano in a non-title match after interference by Theory. During NXT TakeOver: Vengeance Day, Lumis abducted Theory from The Way before Gargano's North American title match. On the February 24 episode of NXT, Lumis defeated Gargano in a non-title bout where Theory hesitated to hit him with a chair, and The Way's Indi Hartwell began to develop an attraction towards him. On April 7, during night one of NXT TakeOver: Stand and Deliver, he took part in a six-man gauntlet eliminator match where the winner won the right to challenge for the North American Championship on night two, but was eliminated second by LA Knight. On the following week's NXT, Lumis teamed with Bronson Reed and the NXT Women's Tag Team Champions Shotzi Blackheart and Ember Moon in an eight-person mixed tag team match against The Way, where he carried a falsely unconscious Hartwell away from the ring.
On August 17, Indi Hartwell proposed to Lumis after the pair won a match on NXT, and Lumis accepted. Lumis and Hartwell had their wedding on the September 14 edition of NXT. During the ceremony, Lumis choked out the priest, allowing a recently ordained Beth Phoenix to take over. Lumis also spoke his very first words in WWE by saying "I do". On April 29, 2022, Lumis was released from his WWE contract.
Lumis returned to WWE on the August 8, 2022 edition of Monday Night Raw. His return was preceded by subtle references such as a car wreck during a backstage segment as well as cops running to the source of trouble. He could be seen in the crowd at the end of the main event between AJ Styles and The Miz, where police officers arrested him and hauled him away. On the August 22 episode of Raw, Lumis kidnapped The Miz during a tag team match. The following night, on the August 23 edition of NXT, Lumis would reunite with his wife Indi Hartwell to briefly reform InDex before being arrested by police. On the August 29 episode of Raw, Lumis would distract Miz, costing him a match against Bobby Lashley. The following week on the September 5 episode of Raw, Lumis would distract Miz again and cost him a cage match against Lashley. After the match, Lumis attacked Miz. On the October 17 edition of Monday Night Raw, Lumis was attacked by the Miz before their match, which would not take place. On the October 31 edition of Raw, Johnny Gargano was interviewed backstage and showed footage of a conversation between The Miz and Lumis where Miz paid Lumis to stage “attacks” on him. On the November 29 episode of Raw, Lumis defeated the Miz in an "Anything Goes" match, earning himself a WWE contract and the money Miz owed him. On the December 19 episode of Raw, Lumis put his money on the line against Miz in a ladder match, which he lost after interference from the returning Bronson Reed.
Lumis appeared at NXT Stand and Deliver in April 2023, assisting Indi Hartwell in her ladder match to win the NXT Women's Championship. He again appeared on the May 2 NXT in a segment with Hartwell.
On the June 17, 2024 episode of Raw, after more than a year since last appearing on television, Lumis made his return as a part of a new stable under the leadership of Uncle Howdy called The Wyatt Sicks. Lumis would sport a buzzard mask, resembling Mercy the Buzzard from Bray Wyatt's Firefly Funhouse. On the July 29 episode of Raw, Lumis, along the Wyatt Sicks stable, unmasked themselves, sporting a new look with a long beard and long dreaded hair.