Promoters Dana White and Tom Loeffler have been building Callum Walsh at a grassroots level for the last four years, and the junior middleweight contender will get his breakthrough chance Sept. 13 when he faces Fernando Vargas Jr. as the co-main event to the superfight featuring Canelo Alvarez and Terence Crawford.

Walsh (14-0, 11 KOs) will officially graduate from headlining shows on UFC Fight Pass, having fought in Southern California casinos and The Theater at Madison Square Garden, to being a face for TKO Group’s Zuffa Boxing when he steps inside the ring at Allegiant Stadium in Las Vegas. The fight will stream globally on Netflix.

“I was definitely surprised I got the co-main event slot of a massive card. It's an honor,” Walsh told The Ring. “It's a very good moment and opportunity for me to show my skills and show how good of a fighter I actually am against another good opponent who has a good name. We are two young and hungry undefeated fighters who are ready to put it all on the line. This fight definitely has the potential to steal the show and be the fight of the night.”

Walsh has been a known commodity in combat sports circles due to his affiliation with the UFC. White, the CEO of Zuffa Boxing and UFC, has shown an affinity for the Irishman since the 24-year-old made his pro debut in 2021.

Walsh is handled by Loeffler’s 360 Promotions and has long billed himself as “the boxer fella with UFC” across his social media profiles. He’s gotten some serious shine during UFC and WWE events in recent years, and even his girlfriend, Tabatha Ricci, is a UFC fighter.

MMA and wrestling rubs aside, the Freddie Roach-coached Walsh insists he’s the real deal in arguably boxing’s deepest division.

“I definitely have a lot more UFC fans than boxing fans right now, but this fight will change everything,” said Walsh, who’s already ranked by three of the sanctioning bodies. “It will show the boxing fans that I am a legitimate fighter and a world-level boxer who's ready to go to the next level.

“I've been boxing since I was six years old and was a six-time Irish champion and European gold medalist. I came on the scene recently, but I've been working for this my whole life. It feels great that it's finally paying off on a worldwide stage.”

Outside of boxing, Walsh is already crossing over into the mainstream by becoming a boon for brands sitting at the intersection of fashion, performance and culture. Just as he evolves into a face for Zuffa Boxing, Walsh is a face for jewelry brand Jaxxon and sister clothing company Santo Studio. Bear Degidio, who leads both companies, has backed Walsh by unveiling custom lines bearing the fighter’s name and has even launched a boxing gym in Newport Beach, California, with the fighter as a flagbearer for the fitness center.

“I got lucky with the unbelievable team that I have in Dana, Tom, Freddie and Bear,” said Walsh. “They are working hard behind the scenes, and I am going out there and working hard too, and doing my job with exciting fights.

“The pressure will not get to me. I have fought on big stages all over the world. I always rise to the occasion and perform my best against a good opponent. I'm going to come away with the win against Vargas.”

Walsh is confident he can crush the second-generation fighter Vargas (17-0, 15 KOs), the son of two-time junior middleweight titleholder Fernando “El Feroz” Vargas. The younger Vargas emerged as an opponent immediately after Walsh’s most recent fight in June, when he survived a nasty eye gash to score a fifth-round technical decision against Elias Espadas.

“I think he's OK. He's fast,” said Walsh. “I think he has what everybody has — a puncher's chance. But I believe I have a lot more skills, experience, and power. I've fought better competition than he has as well, and overall I am a better fighter.”

DraftKings lists Walsh as a minus-295 betting favorite to beat the plus-225 betting underdog Vargas. If Walsh wins the 10-rounder, his Zuffa Boxing career will be a zesty one in 2026 once TKO unveils its planned slate of boxing events.

“I have to show that I can perform under pressure and on the big stage,” said Walsh. “This is an important debut for me under the TKO banner to show my skills to everyone. I'm looking to make a statement that I am not an average fighter.”