ONE Championship

Founding and early history: 2011–2014

Entrepreneur Chatri Sityodtong founded One Fighting Championship (ONE FC) in July 2011 to unite Asia through martial arts, leveraging Singapore's infrastructure. The promotion debuted on 3 September 2011 with ONE FC: Champion vs. Champion, selling out the Singapore Indoor Stadium. Key milestones included the first female MMA bout in March 2012 and the crowning of inaugural champions in bantamweight (Soo Chul Kim), lightweight (Kotetsu Boku), featherweight (Honorio Banario), welterweight (Nobutatsu Suzuki), flyweight (Adriano Moraes), and middleweight (Igor Svirid) divisions between 2012 and 2014.

Name change and expansion: 2015–2019

Rebranded as ONE Championship in 2015, the promotion expanded into new disciplines and markets. It introduced the strawweight title (Dejdamrong Sor Amnuaysirichoke, 2015), hosted its first Lethwei bout (2015), and crowned heavyweight (Brandon Vera, 2015), light heavyweight (Roger Gracie, 2016), and women's atomweight (Angela Lee, 2016) champions.

On February 12, 2018, ONE Championship announced the establishment of the ONE Super Series, which would feature kickboxing and Muay Thai bouts. The first event that featured bouts under Muay Thai and kickboxing rules was ONE: Heroes of Honor in Manila on 20 April 2018. The promotion signed notable names such as Giorgio Petrosyan, Nong-O Gaiyanghadao and Fabio Pinca to feature on the bill. Since the inception of ONE Super Series, some events have used a five-roped ring, instead of the ONE circular cage, which had been used exclusively up until 2018. The ONE Super Series kickboxing bouts adopt the oriental ruleset.

A historic 2018 trade with the UFC exchanged Ben Askren for Demetrious Johnson. The promotion also launched Muay Thai (Sam-A Gaiyanghadao, 2018) and kickboxing titles (Kai Ting Chuang, 2018), and hosted its sole boxing match (Srisaket Sor Rungvisai vs. Iran Diaz, 2018). The first ONE event to consist entirely of ONE Super Series contests was ONE Championship: Immortal Triumph in Ho Chi Minh City on 6 September 2019.

Since 2020, ONE Super Series kickboxing bouts use boxing gloves, while Muay Thai bouts use open-finger 4 oz gloves.

Further international expansion: 2020–Present

ONE raised 150 million in 2021, reaching a 1.35 billion valuation, and relocated to the Cayman Islands in 2022. It expanded into submission grappling (Mikey Musumeci, 2022) and debuted in the U.S. with ONE Fight Night 10 (2023). Notable milestones included Smilla Sundell becoming the youngest champion (17) in 2022 and a 2023 agreement to host events in Qatar.

In 2023, the promotion began a new series of weekly events called ONE Friday Fights, also known as ONE Lumpinee in Thailand, at Bangkok's Lumpinee Stadium, initially scheduling 53 events there during the year; the series was predominantly centered on Muay Thai and featured established Thai fighters and emerging prospects. Since then, Muay Thai bouts became increasingly prominent, while MMA and submission grappling were pushed into the background in ONE's weekly programming, although MMA remained a major part of the promotion's international events.

ONE Championship currently uses ten different weight classes:

ONE weigh-ins include a hydration test.

The change took place after the death of 21-year-old Chinese fighter, Yang Jian Bing (who was supposed to face Geje Eustaquio) on 11 December 2015, due to dehydration by weight-cutting in the Philippines.

The promotion banned weight-cutting by dehydration in order to promote fighter safety. The promotion's revised policy on weight mandated that athletes are monitored in their training camps, and have urine specific gravity tests to ensure they are hydrated up to three hours ahead of their bouts.

Controversies

Former ONE Championship fighter Herbert Burns has alleged that the promotion shows favoritism to athletes signed to Evolve MMA, which was founded by ONE CEO Chatri Sityodtong. After five straight victories, he claimed that it had been agreed that he would fight for the championship, but after leaving Evolve in September 2015, he was "punished" by being sidelined for next two years. Burns said he then accepted non-title fights without being 100 percent physically because he needed money after the time off.

Other former fighters have also expressed frustration with getting fights with ONE Championship. After parting ways with them in December 2023, former ONE Bantamweight Champion Bibiano Fernandes urged fighters to think twice about signing with the promotion. "I wasn't mad at them. Do I think they could have offered me more fights? One-hundred percent. I was out for three years basically and they could have offered me more fights." Fernandes went on to say, "I'm a mixed martial arts fighter but they're doing business. They only think about business, you know? What can I do?".

After leaving the company, former ONE two-division champion Reinier de Ridder also urged fighters not to sign with the promotion. "It's that simple. You should not. There's nothing there. There's no fights. You're just wrong if you do this, if you sign there, this is a bad mistake." After losing the light heavyweight title in December 2022, De Ridder did not fight for the entirety of 2023 before returning to defend the middleweight title in March 2024 in what was his last fight with ONE Championship. "It's been a bad couple of years. The stress I've been put through. The stress my family's been put through. To even just get fights, it hasn't been nice. It's hard for me to talk bad because I had a couple of good years at ONE as well. In the beginning, they treated me well. Over the past couple of years, it's been really bad."