On February 27, 2005, Dillinger made an appearance on an edition of WWE Heat, unsuccessfully teaming with Mikael Yamaha to face The Hurricane and Rosey.
He made a cameo appearance at Cyber Sunday 2006 as an employee called "Stan", who was superkicked by Shawn Michaels of D-Generation X when Michaels was told that he doesn't understand the meaning of the word "controversial".
On the August 19, 2008 episode of ECW, Dillinger made his WWE television debut as a heel under the name Gavin Spears, as part of Theodore Long's "New Superstar Initiative", in a losing effort to Ricky Ortiz. On the September 2 edition of ECW, Spears was defeated by Super Crazy. After a three-month absence, Spears returned to television on the December 16 episode of ECW, where he lost to Finlay in what turned out to be his final match for the company. On January 9, 2009, Spears was released from his contract.
On September 15, 2013, it was reported that Spears had re-signed with WWE, and he was assigned to their developmental territory NXT, under the ring name Tye Dillinger. He made his televised NXT debut in a losing effort against Mojo Rawley. In early 2014, Dillinger formed a tag team with Jason Jordan, with the two described as a pair of blue chip athletes. The team of Dillinger and Jordan got their first televised win on the April 17 episode of NXT, defeating Baron Corbin and Sawyer Fulton. On the June 5 episode of NXT, Dillinger and Jordan defeated local competitors. On the August 7 episode of NXT, Dillinger and Jordan lost in the first round of a NXT Tag Team Championship tournament to Enzo Amore and Colin Cassady. Dillinger and Jordan then appeared infrequently together, with Dillinger mostly being used as enhancement talent. On the February 25, 2015 episode of NXT, Dillinger's partnership with Jordan officially ended when Jordan, unhappy with his partner not initially tagging him in, jumped off the apron and walked out on Dillinger just as he went to make the tag. After the match, an enraged Dillinger called out his old partner but instead was met with a quick loss to Baron Corbin.
On the August 12 episode of NXT, Dillinger debuted a new gimmick as the "Perfect 10" and defeated Solomon Crowe. At NXT TakeOver: Brooklyn, Dillinger faced the debuting Apollo Crews in a losing effort. On the April 27, 2016 episode of NXT, he defeated Buddy Murphy. He faced the debuting Andrade "Cien" Almas at NXT TakeOver: The End, where Dillinger was defeated, although he received praise for his performance.
On the September 28 episode of NXT, after defeating Angelo Dawkins, Dillinger was approached by Bobby Roode, who proposed the two team up for the 2016 Dusty Rhodes Tag Team Classic, which Dillinger accepted. The following week, Dillinger and Roode took on SAnitY (Alexander Wolfe and Sawyer Fulton). During the match, Roode walked out on Dillinger, resulting in the team losing in the first round. The following week on October 19, Dillinger called out Roode for a match at NXT TakeOver: Toronto, which Roode won. On the December 14 episode of NXT, Dillinger defeated Eric Young by disqualification in a number one contender fatal four way qualifying match. At NXT TakeOver: San Antonio, Dillinger was defeated by Young following a distraction from Alexander Wolfe and Killian Dain. At NXT TakeOver: Orlando, Dillinger teamed up with Roderick Strong, Kassius Ohno and Ruby Riot to take on SAnitY in an 8-person mixed tag team match in a losing effort. Dillinger made his last NXT appearance on the April 5 tapings, closing out the event by winning a steel cage match against Eric Young.
On January 29, 2017, at the Royal Rumble, Dillinger was a surprise entrant in the Royal Rumble match, entering at number ten, but was eliminated by Braun Strowman. On the April 4 episode of SmackDown Live, Dillinger would make his main roster debut, defeating Curt Hawkins. Dillinger would enter a short feud with Aiden English, defeating him on various episodes of SmackDown Live, leading to a match at Backlash, where Dillinger once again defeated English to end their feud.
On the July 4 episode of SmackDown Live, Dillinger would compete in an Independence Day battle royal to determine the number one contender to the United States Championship, lasting until the final three before being eliminated by Sami Zayn. At Battleground, Dillinger briefly reignited his feud with English, with Dillinger facing him in a losing effort. On the August 29 episode of SmackDown Live, Dillinger would confront and brawl with Baron Corbin, who was about to answer an open challenge set by AJ Styles for the United States Championship. After Dillinger would fight off Corbin, he would take on Styles' challenge in a losing effort. On the September 12 episode of SmackDown Live, Dillinger would get another shot at the title against Styles, once again in a losing effort. After trading victories with Corbin on various episodes of SmackDown Live, both Dillinger and Corbin would challenge Styles for the United States Championship at Hell in a Cell in a triple threat match, where Corbin would win the title. On the December 26 episode of SmackDown Live, Dillinger would compete in a United States Championship tournament, after former champion Dolph Ziggler vacated the title the week before, where Dillinger would be defeated by Jinder Mahal in the first round.
At the Royal Rumble, Dillinger was to be the number ten entrant in the Royal Rumble match, but was attacked backstage by Kevin Owens and Sami Zayn, with Zayn taking his spot. At Fastlane, Dillinger would team with Breezango (Fandango and Tyler Breeze), defeating the team of Chad Gable, Shelton Benjamin and Mojo Rawley. At WrestleMania 34, Dillinger would compete in the André the Giant Memorial Battle Royal, where he was eliminated by Matt Hardy. In his final pay-per-view appearance, Dillinger competed in the Greatest Royal Rumble, where he entered at number forty-two, but was eliminated by Braun Strowman. On the July 10 episode of SmackDown Live, Dillinger was scheduled to face Samoa Joe, however, Joe attacked him after the match. This led to Dillinger challenging Joe the next week in a losing effort. At a WWE live event on August 13, Dillinger was injured in a match with Shelton Benjamin. The referee called for the end of the match, giving Benjamin the win via count out. Dillinger was promptly escorted backstage by officials. Dillinger returned on the September 25 episode of SmackDown Live, challenging Shinsuke Nakamura for the WWE United States Championship; however, he was attacked during the match by Randy Orton, in what was Dillinger's last televised match with the company.
Dillinger suffered a hand injury in October 2018, which kept him out of action for several months. He returned to in-ring competition at a house show on February 9, 2019; however, he was still not used on television. On February 22, 2019, Dillinger was released from his WWE contract.
At NXT Vengeance Day on February 4, 2024, a mysterious vignette was played. These continued across episodes of NXT until the February 27 episode, when, as Ridge Holland was cutting an in-ring promo, the lights went out and another cryptic vignette was shown, stating that the "truth would be brought to light". Dillinger then made his return to WWE by attacking Holland with a steel chair and being referred to as Shawn Spears, establishing himself as a heel in the process. In his first singles match for the company since 2019, Spears defeated Uriah Connors on March 5 at NXT Roadblock. After the match, Spears cut a promo on Holland, leading to Spears getting attacked by Holland. On the June 25 episode of NXT, Spears defeated NXT Champion Trick Williams in a non-title match. NXT General Manager Ava then announced that Spears, along with Je'Von Evans and Ethan Page, would face Williams for the title in a fatal four-way match at Heatwave, which was later made official. At the event on July 7, Page pinned Evans to become the new NXT Champion.