5 biggest betting underdog wins in 2025 so far

2025 has already delivered a string of genuine shockers in the professional boxing world. We’re talking about nights when the market’s moneyline favourites were toppled and bettors who backed the outsiders were handed big payday headlines. Here, we’ll check out the five biggest boxing upsets this year.

What happened in each fight? How big did these boxing betting odds shock fans? Why do results always matter in sport? Keep scrolling to find out detailed information about this interesting topic.

Boxing upsets – José “Armando” Resendiz vs Caleb Plant

This is the single biggest shock in this list, and it purely comes from the perspective of betting odds. Caleb Plant went into the Michelob Ultra Arena as an overwhelming favourite. The market lines put Plant around -2000, implying roughly a 95-96% chance; on the other hand, Resendiz was offered in the +1000 to +1100 area. That makes Resendiz one of the largest payoff underdogs to win a meaningful bout in 2025.

The context played out as a surprisingly clear stylistic mismatch. Resendiz repeatedly took the centre and landed heavier leather on the inside and by punch count, outworked Plant across the card. Two scorecards favoured Resendiz, and the split decision was announced to a stunned crowd. Several outlets called it a major upset. At the end of it all, many bettors’ who had backed Resendiz at big prices were rewarded handsomely.

The lesson here is to never assume raw reputation equals safety when odds are extreme. Lines like -2000 imply that the books see virtually zero risk. This is exactly when a contrarian bettor should re-check film, recent activity, stylistic matchups, and rust indicators. In this case, Plant’s style and Resendiz’s inside power made the +1000 market price a meaningful value in hindsight.

Rolando “Rolly” Romero crushed Ryan Garcia

Ryan Garcia was widely expected to win. Pre-fight charts showed Garcia as the heavy market favorite. Various books showed Garcia as short as -1200, and Romero was generally in the +550 to +680 band. That gap made Romero’s unanimous decision a sizable market upset.

Romero dropped Garcia early and then boxed disciplined enough to keep Garcia from finding his best shots. Judges awarded Romero a unanimous decision. Coverage called it a seismic upset that disrupted plans for an instant Garcia vs Devin Haney rematch. The fight’s odd setting didn’t change the fact that the results were decisive.

Big names equals big market liquidity, which sometimes leads to exaggerated favourites. When a popular fighter is short-priced after a layoff or controversy, odds can overstate certainty. In this case, careful handicapping, like looking at recent ring rust, weight changes, and mental pressure, pays off. 

Tiara Brown shocks Skye Nicholson for WBC featherweight title

Tiara Brown came into the fight as a clear underdog. Markets priced Nicolson heavily favoured with ~⅛ and Brown at around 5/1. Yet, Brown left Sydney with the WBC belt after a split decision. For many, that result was among the season’s most emotional and unexpected title changes.

Brown travelled to Nicolson’s home arena and executed a pressure, inside-punching game that interrupted Nicolson’s rhythm. The cards were mixed (split decision), and controversy followed. Some called one judge’s 97-93 score “wide.” Regardless, the underdog walkaway victory was confirmed on the official scorecards. This was one of the biggest boxing upsets this year.

Why did this matter, though? Well, world-title upsets at featherweight aren’t common. So, this outcome elevates Brown’s stock significantly and dents Nicolson’s unbeaten aura. For bettors, it is a reminder that stylistic fits and home-advantage assumptions can be overturned by hunger plus pressure tactics. 

Ekow Essuman outworks Josh Taylor in Glasgow

Josh Taylor arrived with much higher name recognition and was the betting favorite. The lines generally had Taylor around -280 to -330 and Essuman at about +225 to +240. Essuman winning a unanimous decision in Scotland, against a former undisputed champion attempting a move up in weight, was registered as one of the biggest boxing upsets in 2025, due to Taylor’s resume.

The bout was competitive early, but Essuman’s work rate and conditioning told in the late rounds. Taylor’s move to welterweight and questions about his stamina contributed. So, the highest score for Essuman in all cards. The match was described as a career-defining night for Essuman and a sobering one for Taylor. 

For bettors, this upset emphasises how weight changes and age can quietly compress true probabilities that bookmakers don’t always reflect. So, if you see a favourite climbing weight classes or returning after hard fights, check stamina and inside work metrics before betting. It might just be eye-opening.

Aaron McKenna beats former champ Liam Smith at Tottenham

While the market in McKenna vs Smith was tighter because some books had McKenna’s favorite, this result still qualifies as an upset in the narrative sense. In that, a young Irish prospect could put away a recognisable ex-world champion on a huge London card. This career-making easily altered expectations and market lines for the division. The outcome was treated like a shock because of Smith’s name and past belt. 

The win accelerated McKenna’s ascent for bookmakers and handicappers. It is a convincing win over a former world champion, and this triggered fast line movement in future fights and changes where value can be found. This also reminded bettors that prospects with momentum can beat name recognition when the styles or physicals favour the younger fighter. 

However, don’t confuse pedigree with current form. McKenna’s victory emphasises the value of recent form, momentum from ring activity, to young legs. This refers to a situation when sizing bets against older ex-champions.

Bet responsibly & wisely!

Most, if not all, of the matches mentioned in this article are stories of when the least expected athlete becomes the victorious one. In this case, many people end up losing their bets. However, this is not a call to bet irresponsibly.

Betting should be entertainment, whether your favourite team of athletes wins or not. These results serve as reminders that relations, past glories or short-priced odds never guarantee victory inside the ring. As the year is running out, you can expect more boxing upsets in the wings. So, brace yourself!