At NXT TakeOver: Brooklyn III on August 19, Bobby Fish and Kyle O'Reilly debuted as a team, attacking the newly-crowned NXT Tag Team Champions SAnitY (Alexander Wolfe and Eric Young), as well as their opponents for the night, The Authors of Pain. Later that night, the two aligned themselves with Adam Cole and attacked newly-crowned NXT Champion Drew McIntyre. The following month, the trio of Cole, Fish and O'Reilly was officially dubbed "The Undisputed Era".
On the October 11 episode of NXT, Taynara Conti interfered in a triple threat match between Nikki Cross, Peyton Royce and Liv Morgan on behalf of The Undisputed Era, preventing Cross of SAnitY from winning. At NXT TakeOver: WarGames, The Undisputed Era defeated SAnitY and The Authors of Pain and Roderick Strong in a WarGames match, the first of its kind in twenty years. On the December 20 episode of NXT, (taped on November 29), Fish and O'Reilly defeated SAnitY (Eric Young and Killian Dain) to capture the NXT Tag Team Championship, marking their first title win in WWE. On the January 10, 2018 episode of NXT, Fish and O'Reilly were scheduled to defend their titles against SAnitY in a rematch, but assaulted them backstage, rendering them unable to compete. Later that night, they were forced to defend their championships against Aleister Black and Strong by NXT general manager William Regal, and successfully retained their titles after Cole interfered and distracted Black. At NXT TakeOver: Philadelphia, The Undisputed Era defeated The Authors of Pain to retain the titles. On March 4, Fish suffered a torn ACL and MCL in his left knee at an NXT live event.
On April 7 at NXT TakeOver: New Orleans, Cole became the inaugural NXT North American Champion in a ladder match also involving EC3, Killian Dain, Lars Sullivan, Ricochet and Velveteen Dream. Later in the night, O'Reilly and Cole (in place of the injured Fish) successfully defended the NXT Tag Team Championships in the finals of the 2018 Dusty Rhodes Tag Team Classic against The Authors of Pain and Strong and Pete Dunne after Strong turned on Dunne to allow O'Reilly to pin him, joining the stable and turning heel in the process and allowing the group to win the tournament despite not being in it originally. With Strong joining the group, he was also recognized as part of the NXT Tag Team Champions. At NXT TakeOver: Chicago, O'Reilly and Strong successfully defended the titles against Danny Burch and Oney Lorcan.
After developing a rivalry with British Strong Style (Dunne, Trent Seven and Tyler Bate), the two factions faced off on the first day of the WWE United Kingdom Championship Tournament event, where The Undisputed Era lost. On the second day of the event, O'Reilly and Strong lost the NXT Tag Team Championship to Seven and Bate. However, O'Reilly and Strong regained the titles just two days later (aired on tape delay on July 11). With the win, O'Reilly and Strong became just the second team in NXT history to win the titles more than once (the other being The Revival (Dash Wilder and Scott Dawson). At NXT TakeOver: Brooklyn 4, O'Reilly and Strong retained their titles against Bate and Seven. After the match, O'Reilly and Strong were attacked by the debuting War Raiders (Hanson and Rowe). On the same night, Cole lost the North American Championship to Ricochet.
On the August 29 episode of NXT, Cole and Strong defeated Ricochet and Dunne and attacked them along with O'Reilly after the match. However, the War Raiders came to the ring, chasing The Undisputed Era away. On the October 10 episode of NXT, Ricochet defeated Cole and Dunne in a triple threat match to retain the North American Championship. On the October 17 episode of NXT, O'Reilly and Strong retained the NXT Tag Team Championship against the War Raiders by disqualification after Fish returned from injury and attacked Hanson and Rowe. On the October 31 episode of NXT, Cole and Fish were scheduled to face the War Raiders. However, Hanson and Rowe attacked The Undisputed Era during a backstage promo. The brawl ended up in the ring, where The Undisputed Era got the upper-hand. Ricochet and Dunne entered on the War Raiders' behalf as the brawl progressed to even the odds. While the groups were fighting, general manager William Regal announced that The Undisputed Era would face the team of the War Raiders, Ricochet and Dunne in a WarGames match at NXT TakeOver: WarGames. At the event, The Undisputed Era were defeated after both Ricochet and Dunne pinned Cole. At NXT TakeOver: Phoenix, The Undisputed Era lost the NXT Tag Team Championships to The War Raiders.
All four members competed at NXT TakeOver: XXV. Strong lost to Matt Riddle in the opening match, Fish and O'Reilly were unsuccessful in a four-way ladder match for the vacant NXT Tag Team Championship, and, in the event's main event, Cole defeated Johnny Gargano to win the NXT Championship. The win made Cole the second Triple Crown winner in NXT history (behind Gargano). On the August 15 tapings of NXT, O'Reilly and Fish defeated Street Profits (Angelo Dawkins and Montez Ford) for the NXT Tag Team Championships, making O'Reilly the first wrestler to become a three-time NXT Tag Team Champion. On September 18, 2019, Roderick Strong defeated Velveteen Dream for the NXT North American Championship, marking Strong's first singles title in WWE, and making The Undisputed Era the first group to be draped in gold and hold all male championships on the NXT brand.
In the build-up for the NXT and NXT UK co-branded pay-per-view, Worlds Collide, The Undisputed Era began feuding with Imperium (WWE United Kingdom Champion Walter, Alexander Wolfe, Fabian Aichner and Marcel Barthel), which was further intensified during the closing moments of NXT UK TakeOver: Blackpool II on January 12, 2020, where the group attacked Imperium following Walter's successful title defense against Joe Coffey. At Worlds Collide, Imperium defeated The Undisputed Era despite being outnumbered 4-3 after Wolfe suffered an injury early in the match. In parallel, Strong lost his title to Keith Lee, while Fish and O'Reilly took part in the 2020 Dusty Rhodes Tag Team Classic, defeating NXT UK Tag Team Champions Gallus (Mark Coffey and Wolfgang) in the first round and losing to Grizzled Young Veterans (James Drake and Zack Gibson) in the semifinals thanks to a distraction from Imperium.
At NXT TakeOver: Portland, Cole successfully retained his title against Tommaso Ciampa after receiving assistance from the rest of The Undisputed Era and Johnny Gargano, who attacked Ciampa with the belt. However, Fish and O'Reilly lost the tag team titles to Dusty Rhodes Tag Team Classic winners The BroserWeights (Matt Riddle and Pete Dunne), leaving The Undisputed Era with only one title for the first time since August 2019. On the April 22 episode of NXT, Velveteen Dream and Dexter Lumis (replacing Keith Lee, who was attacked by Damian Priest before the match) defeated Cole and Strong in a tag team match, where Dream pinned Cole. This led to an NXT Championship match on the May 6 episode of NXT, where Cole successfully retained his title against Dream and again at NXT TakeOver: In Your House on June 7 in a last chance Backlot Brawl match, due to the stipulation at the event where if Dream lost he can no longer challenge for the NXT Championship again while Cole was still champion. Roderick Strong would then enter a feud with Dexter Lumis. On the June 17 episode of NXT, Roderick Strong would undergo therapy to get over his fear of Lumis. On the June 24 episode of NXT, Strong and Lumis would face each other but Lumis would win via countout after Strong refused to fight Lumis.
On the July 1 episode of NXT: The Great American Bash, Strong would face Lumis in a strap match, but lost, thus ending their feud. On the July 8 episode of NXT: The Great American Bash, Cole would lose the NXT Championship to Keith Lee in a Winner Take All match, ending his historic reign at 403 days. Though Cole later turned face after entering into a feud with Pat McAfee, Fish and Strong remained as heels. On the September 8 episode of NXT, Fish and Strong entered into a feud with Killian Dain, with Drake Maverick making the save and the Undisputed Era running off. On the September 16 episode of NXT, O'Reilly turned face after saving Jake Atlas from a beatdown at the hands of Tommaso Ciampa. On the September 23 episode of NXT, O'Reilly would win a gauntlet match earning him a title match against Finn Bálor at NXT TakeOver: 31. Cole cemented his face turn on the September 30 episode of NXT after calling out Austin Theory, who had insulted O'Reilly earlier in the night during a backstage promo. At NXT TakeOver: 31, O'Reilly would lose to Finn Balor.
On October 21, Fish and Strong were mysteriously attacked before their tag team title match against Breezango and were replaced by Oney Lorcan and Danny Burch. It was revealed that Pat McAfee was behind the attacks, thus turning all the members of the Undisputed Era into fan favorites. At NXT: Halloween Havoc, Kyle O' Reilly would confront McAfee, Burch and Lorcan. A returning Pete Dunne would assist Kyle O' Reilly. However this partnership was short lived as Dunne would hit O' Reilly with a steel chair turning heel in the process and aligning himself with McAfee, Lorcan and Burch.
On the November 18 episode of NXT, The Undisputed Era would make their return and brawl with Pat McAfee, Pete Dunne and the NXT Tag Team Champions Oney Lorcan and Danny Burch. William Regal would then announce that the two teams would face each other at NXT TakeOver: WarGames. At NXT Takeover: WarGames, the Undisputed Era would defeat Team McAfee.
Kyle O' Reilly would face Pete Dunne on the December 16 episode of NXT, where the winner would face Finn Balor at NXT: New Years Evil for the NXT Title. O' Reilly would defeat Dunne and earn himself another opportunity at the NXT Title. It was announced in late December 2020 that Adam Cole and Roderick Strong would be teaming up to represent The Undisputed Era in the 2021 Dusty Rhodes Tag Team Classic, where they defeated Breezango in the first round. They would however lose to the team of Timothy Thatcher and Tommaso Ciampa in the quarterfinals.
At NXT TakeOver: Vengeance Day, after saving Finn Bálor from a post match assault from Pete Dunne, Oney Lorcan, and Danny Burch, Cole superkicked Bálor. Following a confrontation, Cole also superkicked O'Reilly, turning Cole heel. On the March 24 edition of NXT, it was announced that The Undisputed Era had officially disbanded. Cole and O'Reilly fight each other in an unsanctioned match at NXT TakeOver: Stand and Deliver, where O'Reilly was victorious. It would be announced that Cole and O'Reilly would face each other in a rematch at The Great American Bash. At the event, Cole would defeat O'Reilly. Cole and O'Reilly would end their feud in a 2-out-of-3 falls match at NXT TakeOver: 36 in a match labeled "The Undisputed Finale", with O'Reilly defeating Cole. After a brief feud with Roderick Strong, Bobby Fish was released from his WWE contract and Adam Cole would depart WWE in September.