Through NJPW's working relationship with Mexican promotion Consejo Mundial de Lucha Libre (CMLL), Devitt also wrestled there, becoming a one-time NWA World Historic Middleweight Champion.

He made his debut in a triple threat match at Soul Survivor III on 5 November, challenging for the MWF Television Championship against the champion Eddie Edwards and R. J.

Following the injury, he returned to action, showing great improvement and was touted by fellow CTU teammate, Minoru, as the future winner of the 2007 Best of the Super Juniors tournament.

[33] On 4 January 2010, at Wrestle Kingdom IV in Tokyo Dome, Devitt and Taguchi successfully defended the IWGP Junior Heavyweight Tag Team Championship against Averno and Último Guerrero.

[37][38] On 13 June, Devitt first defeated Taiji Ishimori in the semifinals and then Kota Ibushi in the finals to win the tournament and earn a shot at Naomichi Marufuji's IWGP Junior Heavyweight Championship.

[40] Eleven days later, Devitt, Taguchi and Hirooki Goto won the J Sports Crown Openweight 6 Man Tag Tournament, defeating Hiroshi Tanahashi, TAJIRI and Kushida in the finals.

[45] Devitt managed to win four out of his seven matches in the round-robin stage of the tournament, including a major victory over former four-time IWGP Heavyweight Champion Hiroshi Tanahashi, but finished fifth in his block and missed advancing to the finals by a single point.

[46][47] On 3 September, Devitt made his second successful defense of the IWGP Junior Heavyweight Championship, defeating DDT Pro-Wrestling representative Kenny Omega, that he won on 11 November 2012.

[69] On 10 October at Destruction '11, Devitt and Taguchi lost the IWGP Junior Heavyweight Tag Team Championship to the No Remorse Corps (Davey Richards and Rocky Romero).

[76] On 14 March 2012, Devitt traveled to Mexico for his first tour of the country with the Consejo Mundial de Lucha Libre promotion, as part of a working relationship between New Japan and CMLL.

[77][78] After being sidelined from in-ring action due to a calf injury for his first week in Mexico, Devitt made his CMLL debut on 23 March, teaming with Marco Corleone and Rush in a six-man tag team main event, where they faced Mephisto, Último Guerrero and Volador Jr. After pinning Volador Jr. for the win, Devitt challenged him to a match for the NWA World Historic Middleweight Championship.

[96][97] On 21 October, Apollo 55 entered the 2012 Super Jr. Tag Tournament, defeating Chaos World Wrestling Warriors (Brian Kendrick and Low Ki) in their first round match.

[100][101] On 4 January 2013 at Wrestle Kingdom 7 in Tokyo Dome, Devitt defeated Low Ki and Kota Ibushi in a rare three-way match for his first successful defense of the title.

[110] Two days later at Invasion Attack, Apollo 55 unsuccessfully challenged Time Splitters for the IWGP Junior Heavyweight Tag Team Championship, after which Devitt turned on Taguchi, ending the longtime partnership between the two, and debuted Bad Luck Fale as his new "bouncer", while also dubbing himself the "Real Rocknrolla".

[141][142] On 4 January 2014 at Wrestle Kingdom 8 in Tokyo Dome, Devitt's fourteen-month reign as the IWGP Junior Heavyweight Champion came to an end when he lost the title to Kota Ibushi in his fifth defense.

[151][152] On 24 September, his new ring name was revealed to be Finn Bálor,[153] derived from Irish mythological figures Fionn mac Cumhaill and Balor (the latter is also Gaelic for "Demon King").

[165] Bálor later entered the Dusty Rhodes Tag Team Classic tournament in August, pairing with Samoa Joe and defeating The Lucha Dragons (Sin Cara and Kalisto) in the first round,[166] Enzo Amore and Colin Cassady in the quarter-finals,[167] Dash Wilder and Scott Dawson in the semi-finals and Baron Corbin and Rhyno in the finals on 7 October at NXT TakeOver: Respect to win the tournament.

[192] Over the following weeks, Bálor would score victories over Jinder Mahal and Curt Hawkins[193] while also receiving an ominous warning from Bray Wyatt[194] and confronting Luke Gallows and Karl Anderson.

[215] At the Greatest Royal Rumble event on 27 April, Bálor once again unsuccessfully challenged for the Intercontinental Championship in a fatal four–way ladder match against Rollins, Miz and Samoa Joe.

[218] After the Money in the Bank pay–per–view, Bálor engaged in a feud with Baron Corbin, whom he defeated on two different occasions—on 15 July at Extreme Rules[219] and on 19 August at SummerSlam under his "Demon King" persona.

[220] The next night on Raw, Bálor was finally awarded with his Universal Championship rematch against newly crowned champion Roman Reigns, but was unsuccessful in regaining the title.

[239] On 14 January episode of Raw, after Braun Strowman was removed from his Universal Championship match against Brock Lesnar at the Royal Rumble after damaging Vince McMahon's limo, Bálor was booked in a fatal-four way match against Drew McIntyre, John Cena and Baron Corbin to determine who would take Strowman's place against Lesnar at the pay-per-view, in which Bálor emerged victorious after pinning Cena.

[259] Bálor made his return on 9 December episode of NXT where he was confronted by O'Reilly, Pete Dunne, Damian Priest and Scarlett (on behalf of Karrion Kross).

[272]At Hell in a Cell on 5 June, Bálor, AJ Styles and Liv Morgan lost to The Judgment Day (Edge, Damian Priest and Rhea Ripley) in a six-person mixed tag team match.

On 8 May episode of Raw, Bálor defeated Cody Rhodes and The Miz in a triple threat match in the first round of the tournament, but lost to eventual champion Seth "Freakin" Rollins in the semifinals later that night.

[286] At the event on 1 July, Bálor was unsuccessful in defeating Rollins for the title after an unintended distraction by Priest, who had just won the Money in the Bank ladder match earlier during the night and seemingly had intentions of cashing in.

[288] On 2 September at Payback, Bálor and Priest defeated Kevin Owens and Sami Zayn to win the Undisputed WWE Tag Team Championship after interference from Dominik, Ripley and JD McDonagh.

[301] On 13 May episode of Raw, Bálor and McDonagh won a fatal four-way match to become the #1 contenders to Awesome Truth's newly renamed World Tag Team Championship after interference from Carlito, who began inserting himself into the group.

[307] At Saturday Night's Main Event on 14 December, Bálor challenged Gunther for the World Heavyweight Championship in a triple threat match also involving Priest, but failed to win the title.

[23] He is good friends with fellow professional wrestlers AJ Styles, Karl Anderson, Luke Gallows, Tama Tonga, Jordan Devlin and Dru Onyx.