Ellsworth first appeared in the WWE a couple of times in 2014, as one of Adam Rose's "Rosebuds". He had his first WWE singles match on the July 25, 2016 episode of Raw as an enhancement talent, being quickly defeated by Braun Strowman. Ellsworth gained some praise and subsequently developed a cult following due to his meek appearance and enthusiastic pre-match promo in which he declared that "any man with two hands has a fighting chance" before being easily defeated by Strowman.
Ellsworth resurfaced in the main event of the September 13 episode of SmackDown Live as the mystery tag team partner for WWE World Champion AJ Styles against Dean Ambrose and John Cena, only to be attacked by Intercontinental Champion The Miz (his replacement in the actual match) as he walked down to the ring. On the October 11 episode of SmackDown Live, Ellsworth was chosen by Styles as his opponent in a non-title match, but SmackDown General Manager Daniel Bryan made Ambrose the special guest referee for the match. Ambrose favored Ellsworth during the match due to his rivalry with Styles, culminating in Ambrose attacking Styles and allowing Ellsworth to win. Ellsworth was granted a WWE World Championship match the following week on the October 18 episode of SmackDown Live, with Ambrose serving as the timekeeper and ring announcer (Ellsworth won the match by disqualification, but not the title). Ellsworth continued to offer assistance to Ambrose in his rivalry with Styles, but this backfired on the October 25 episode of SmackDown Live, when Ellsworth accidentally cost Ambrose the match after executing No Chin Music on Styles, disqualifying Ambrose. On the November 1 episode of SmackDown Live, Ellsworth interfered in the rematch, distracting Styles and allowing Ambrose to win an opportunity for the title. SmackDown Commissioner Shane McMahon also named Ellsworth the SmackDown mascot for the 2016 Survivor Series match on the November 8 episode of SmackDown Live.
During Survivor Series on November 20, Ellsworth helped eliminate Braun Strowman by countout by holding onto his leg, only for Strowman to chase Ellsworth up the ramp and put him through a table, injuring his neck. After legitimately signing a WWE contract, this was worked into a storyline on the 22 November episode of SmackDown Live, when Styles goaded the injured Ellsworth to face him in a ladder match for the right to be a SmackDown superstar with his contract suspended above the ring; Ellsworth agreed, but wanted another shot at the WWE World Championship should he win the match. That night, Ellsworth defeated Styles to win a SmackDown contract, due to Ambrose helping Ellsworth yet again. On the 29 November episode of SmackDown Live, Ellsworth suffered a storyline injury after Styles interrupted his Ambrose Asylum segment with Ambrose, attacking both and delivering a Styles Clash to Ellsworth off the steel steps, which caused Ellsworth to be taken on a stretcher by medical personnel.
This led to Ellsworth interfering on December 4 at TLC: Tables, Ladders & Chairs, during the Tables, Ladders and Chairs match between Styles and Ambrose to help the latter, but he ended up turning heel by helping Styles instead by pushing Ambrose off the ladder and sent him through two tables. Ellsworth explained that since he had already beaten Styles three times, he helped Styles because he wanted to defeat him again, this time for the WWE World Championship, a match SmackDown's Commissioner Shane McMahon granted him for the following episode of SmackDown Live. Ellsworth tried to make it up with Ambrose by helping him defeat The Miz for the Intercontinental Championship on the December 6 episode of SmackDown Live, but his effort backfired and eventually cost Ambrose the match. Ellsworth's title opportunity was twice postponed, first due to Styles being legitimately injured; and the second time due to Ellsworth suffering from a kayfabe cold. The match eventually happened on the December 20 episode of SmackDown, during which Styles easily defeated Ellsworth in under a minute to end their storyline.
After his storyline with Styles and Ambrose ended, Ellsworth allied himself with Carmella. On the January 3, 2017 episode of SmackDown, Ellsworth started accompanying Carmella to the ring for her matches, helping her win. Ellsworth entered the 2017 Royal Rumble match at number 11, but he was eliminated by Braun Strowman after only 15 seconds. Throughout the months of January and February, Ellsworth appeared in various backstage segments with Carmella, often helping Carmella win by distracting her opponents. Ellsworth made his WrestleMania debut on April 2 at WrestleMania 33, managing Carmella in the six-pack challenge for the SmackDown Women's Championship, which was won by Naomi. On April 25, Carmella and Ellsworth formed an alliance with Natalya and the returning Tamina. On the May 16 episode of SmackDown Live, Carmella scored a victory over Naomi in a non-title match via distraction from Ellsworth. Dubbed The Welcoming Committee, the team of Carmella, Natalya and Tamina, managed by Ellsworth, defeated Charlotte Flair, Becky Lynch and Naomi in a six-woman tag team match on May 21 at Backlash. On June 18 at Money in the Bank, Ellsworth helped Carmella win the first ever women's Money in the Bank ladder match by pushing Becky Lynch off the ladder and dropping the briefcase to Carmella.
Two days later on SmackDown Live, Carmella was stripped of the briefcase and a second Money in the Bank ladder match was set by SmackDown General Manager Daniel Bryan for the June 27 episode of SmackDown Live, where Carmella regained the Money in the Bank briefcase after she won the second match, once again with the help of Ellsworth, who was initially banned from the arena. On the following episode of SmackDown Live, Ellsworth was fined $10,000 and suspended for 30 days by Bryan due to his disobedience. Ellsworth returned on the August 8 episode of SmackDown Live and once again interfered and helped Carmella defeat SmackDown Women's Champion Naomi in a non-title match. After weeks of tension, Ellsworth lost an intergender match to Becky Lynch and was attacked by Carmella after the match on the November 7 episode of SmackDown Live, ending his relationship with Carmella as well as marking his last appearance in WWE for nearly a year.
On June 17, 2018 at Money in the Bank, Ellsworth made his return to WWE, by helping Carmella retain the SmackDown Women's Championship against Asuka, reestablishing himself as a heel and reigniting his on-screen relationship with Carmella from 2017 on a night to night contract. At Extreme Rules, Ellsworth was suspended above the ring in a shark cage during Asuka's rematch with Carmella. Ellsworth tried to escape the cage after breaking the lock, only to become entangled and stuck, distracting Asuka and allowing Carmella to defeat her. On the July 24 episode of SmackDown Live, Ellsworth interrupted a SummerSlam WWE Championship contract signing between AJ Styles and Samoa Joe, during which Ellsworth was fired after he insulted General Manager Paige. He later appeared at SmackDown 1000, on a video uploaded to WWE's website and YouTube account, where he claimed he should have been a part of the show.