He is best known for his time in WWE, where he performed on the NXT and 205 Live brands, mostly under the ring name Gentleman Jack Gallagher.

[3] He made his professional wrestling debut at the age of 16 on 4 November 2006 at Futureshock #11, under the ring name Jack Toxic, teaming up with Alex Cyanide, Danny Hope, and Kris Travis.

Claffey, performing as Jack Toxic, made his singles debut at Grand Pro Wrestling West Park Fun Day and lost to Scarlett Web.

At Guts & Glory, he returned under the name Jack Gallagher to compete in a four way scrabble match for the GPW British Championship and lost.

Gallagher made his Grand Pro return at the 2013 Crazy Cruiser 8 where he defeated Bubblegum in the quarter-finals before being pinned by eventual winner El Ligero in the semi-finals.

[15] On 15 April 2013, Anthony came together with Craig Classic, James Raideen, Jason New, Maybach Beta, Sebastian Concrete, Steven Walters and Tama Williams to form a gaijin stable named "New Age Wrestling Future" (NWF) under the guidance of Akebono.

[18] During his time in the independent circuit, he has also made appearances in Progress Wrestling, where he got his biggest win by defeating Pete Dunne for a qualifying position in the WWE Cruiserweight Classic.

On 24 April 2016, Gallagher earned a place in the WWE Cruiserweight Classic by defeating Pete Dunne in a qualifier match at Progress Wrestling's Chapter 29.

[26] On 7 February episode of 205 Live, Gallagher defeated Cedric Alexander, Mustafa Ali, Noam Dar, and T. J. Perkins in a fatal five-way elimination match to become the number one contender for the WWE Cruiserweight Championship.

[28] Gallagher made a guest appearance on 26 April episode of NXT, unsuccessfully challenging Tyler Bate for the WWE United Kingdom Championship in the main event.

[32] On 12 September episode of 205 Live, Gallagher attacked Cedric Alexander during his match with The Brian Kendrick, turning heel in the process.

On 19 December episode of 205 Live, Gallagher and Gulak were defeated by Kendrick and Tozawa in a Street Fight to end the feud.

[38] Starting in February 2019, Gallagher and Gulak attempted to recruit the debuting Humberto Carrillo to their faction while also trying to prevent him from using high flying moves and instead using a more ground based offence.

[41] Gallagher returned on 28 February 2020 episode of 205 Live, attacking Lio Rush, while sporting a beard, shorter hairstyle and new tattoos covering his body.

[42] With his new attitude, Gallagher would develop a winning streak on 205 Live defeating the likes of Tyler Breeze and Oney Lorcan.

Gallagher lost to El Hijo del Fantasma and Akira Tozawa but was able to defeat Isaiah "Swerve" Scott to secure one win in the tournament.

[5] A May 2019 report by the Wrestling Observer Newsletter alleged that there was interest from Bellator MMA about possibly recruiting Claffey for the promotion.

[45] After being released from the WWE, Claffey started training in the sport again, and eventually made his professional debut against Marlon Jones at Full Contact Contender 32 on 17 December 2022.