ONE Championship

Entrepreneur and martial artist Chatri Sityodtong stated his reasons for founding One Fighting Championship in July 2011 was that he believed that martial arts was Asia's "cultural treasure", yet there was no Pan-Asian promotion to unite the continent. "My vision is to make ONE Asia's first multi-billion-dollar sports media property. Every other region has them[...] But there is absolutely nothing like that on a pan-Asian basis." He chose Singapore as the promotion's base because of its location and communications infrastructure.

One Fighting Championship held their first event, ONE FC: Champion vs. Champion, on 3 September 2011 at the sold-out Singapore Indoor Stadium. On 31 March 2012, the promotion held its first female MMA fight during ONE FC: War of the Lions at the same stadium. It saw Nicole Chua, Singapore's first female professional MMA fighter, submit seven time Indian kickboxing champion Jeet Toshi.

On 6 October 2012, ONE crowned its first two champions at ONE FC: Rise of Kings; Soo Chul Kim became the inaugural ONE Bantamweight World Champion by stopping Leandro Issa, and Kotetsu Boku defeated Zorobabel Moreira by TKO to become the inaugural ONE Lightweight World Champion. The inaugural ONE Featherweight World Championship followed on 3 February 2013 at ONE FC: Return of Warriors, where Honorio Banario defeated Eric Kelly.

After having to be rescheduled from 2013, the inaugural ONE Welterweight World Championship bout took place at ONE FC: War of Nations on 14 March 2014. It saw Nobutatsu Suzuki defeat Brock Larson. At ONE FC: Rise of the Kingdom on 12 September 2014, Adriano Moraes became the first ONE Flyweight World Champion after submitting Geje Eustaquio. The ONE Middleweight World Championship was introduced at ONE FC: Battle of the Lions on 7 November 2014, where Igor Svirid defeated Leandro Ataides in 17 seconds for the title.

On 13 January 2015, the promotion announced it would be changing its name to simply "One Championship".

ONE Championship and Ultimate Fighting Championship finalized the first "trade" in MMA history on 27 October 2018. ONE Welterweight Champion Ben Askren was released from his contract so he could sign with the UFC and former UFC Flyweight Champion Demetrious Johnson was released from his contract so he could sign with ONE.

Dejdamrong Sor Amnuaysirichoke became the first ONE Strawweight World Champion after beating Roy Doliguez on 22 May 2015 at ONE: Warrior's Quest. ONE held the first Lethwei fight in its history at ONE: Kingdom of Warriors on 18 July 2015 in Yangon, Myanmar. The fight showcased Burmese fighters Phyan Thway and Soe Htet Oo in a dark match and the result was a draw according to traditional Lethwei rules. At ONE: Spirit of Champions on 11 December 2015, Brandon Vera knocked out Paul Cheng in the first round to become the inaugural ONE Heavyweight World Champion.

The promotion crowned two more inaugural champions at ONE: Ascent to Power on 6 May 2016. Roger Gracie submitted Michal Pasternak for the inaugural ONE Light Heavyweight World Championship. The inaugural ONE Women's Atomweight World Championship title match saw 19-year-old Angela Lee defeat Mei Yamaguchi to become the first female champion in ONE and one of the youngest ever titleholders in combat sports. On 13 August 2016, ONE Championship held its first grappling tournament in Cotai, Macau; One Grappling Challenge Macao took place before ONE: Heroes of the World. Following IBJJF no-gi rules, Angela Lee, Shinya Aoki, and Michelle Nicolini were among the participants.

On 10 November 2017, ONE Featherweight World Champion Martin Nguyen became the promotion's first simultaneous two-division champion when he knocked out Eduard Folayang for the ONE Lightweight World Championship at ONE: Legends of the World.

Xiong Jing Nan defeated Tiffany Teo at ONE: Kings of Courage on 20 January 2018 to win the inaugural ONE Women's Strawweight World Championship. mONE crowned its first champion in Muay Thai at ONE: Unstoppable Dreams on 18 May 2018, when Sam-A Gaiyanghadao stopped Sergio Wielzen for the inaugural ONE Flyweight Muay Thai World Championship. This was followed by ONE's first kickboxing champion at ONE: Battle for the Heavens on 7 July 2018, when the inaugural ONE Atomweight Kickboxing World Championship bout saw Kai Ting Chuang defeat Yodcherry Sityodtong. On 6 October 2018, ONE: Kingdom of Heroes was headlined by Srisaket Sor Rungvisai defending his World Boxing Council championship against Iran Diaz. This is the only boxing match under the ONE Championship banner to date.

February 2019 saw the inaugural ONE Bantamweight Muay Thai World Championship and ONE Atomweight Muay Thai World Championship matches. The former took place on 16 February 2019 at ONE: Clash of Legends, where Nong-O Gaiyanghadao defeated Han Zihao. The latter took place at ONE: Call to Greatness on 22 February 2019, where ONE Atomweight Kickboxing World Champion Stamp Fairtex defeated Janet Todd to become the promotion's first two-sport champion.

2019 also saw the introduction of multiple ONE championship titles in kickboxing. The inaugural ONE Flyweight Kickboxing World Championship match took place at ONE: Warriors of Light on 10 May 2019, where Petchdam Petchyindee Academy defeated Elias Mahmoudi.

In December 2021, ONE raised an additional $150 million through an investing round led by Guggenheim Investments and the Qatar Investment Authority, increasing the company’s valuation to $1.35 billion. In October 2022, One Group Holdings changed its legal domicile from Singapore to the Cayman Islands. On 22 June 2023, it was announced that ONE would be bringing live events to Qatar later in the year, having signed an MoU with Media City Qatar.

17-year-old Smilla Sundell became the youngest champion in ONE history on 22 April 2022, when she defeated Jackie Buntan at ONE 156 for the inaugural ONE Women's Strawweight Muay Thai World Championship.

ONE awarded their first belt for submission grappling on 1 October 2022 at ONE on Prime Video 2, where Mikey Musumeci defeated Cleber Souza for the ONE Flyweight Submission Grappling World Championship.

ONE held its first event in America, ONE Fight Night 10, at the 1stBank Center in Broomfield, Colorado on 5 May 2023. Colorado was chosen because its athletic commission was the first to approve ONE's rule set. The organization had initially planned on debuting in the US years prior, but was ultimately delayed due to the COVID-19 pandemic.