In 2007, the year he turned 20, he made his professional MMA debut at the Super Sambo Festival. In 2008 he beat Michihiro Omigawa by decision on the DEEP stage in Japan and began to make his name internationally. In 2009 he lost for the first time as a pro, to Masanori Kanehara at Sengoku in Japan.
The breakthrough yearIn April 2010, the year he turned 23, he traded strikes with Leonard Garcia for three rounds at WEC 48 in the U.S. and lost a decision. Little known outside some fans until then, he drew wide attention after the fight. That October he lost by KO at WEC 51 after a high kick from George Roop.
In March 2011 he faced Garcia again in his UFC debut and avenged the loss with a twister submission, the first twister win in UFC history. That December he knocked out Mark Hominick in 7 seconds, tying the fastest KO in UFC history at the time. In 2012 he beat Dustin Poirier by D’Arce choke and received two bonuses for the fight.
In April 2013 he began teaching younger fighters at the Korean Zombie MMA gym. That August he lost by TKO to champion José Aldo in the title fight at UFC 163 in Brazil, the first UFC title fight for a Korean. In 2014 he married, and when his shoulder injury recurred he enlisted for social service duty.
In 2016 he finished his social service duty. In 2017 he beat Dennis Bermudez by KO in his UFC return after three and a half years. In May 2018 he signed with the hip-hop label AOMG, the first athlete it had signed. That November he lost by KO to Yair Rodriguez with one second left in the fight.
In June 2019 he beat Renato Moicano in 58 seconds. That December he beat Frankie Edgar in Busan. In 2020 he lost a decision to Brian Ortega. In 2021 he beat Dan Ige by decision.
In 2022 he lost by TKO to champion Alexander Volkanovski at UFC 273. It was his second UFC title fight, nine years after the Aldo fight. In August 2023, the year he turned 36, he lost by KO to Max Holloway in Singapore and announced his retirement. It came 16 years after debut, with a record of 17-8.
In June 2024 he launched the MMA event ZFN and became its head. That December, two fighters from its second event went straight to the UFC. In 2025 he held ZFN 3 at Korea University. It ranked fifth in 2025 UFC Fight Pass replay viewership. In 2026 he invited Alexander Volkanovski, the UFC champion who had beaten him, to Korea.
Chan Sung Jung (born Mar 17, 1987) made his professional MMA debut at the Super Sambo Festival on Jun 24, 2007, the year he turned 20, and became known on Apr 25, 2010, the year he turned 23, for his decision loss to Leonard Garcia at WEC 48. He announced his retirement after a loss to Max Holloway in 2023, the year he turned 36.
Ages are by calendar year (the year minus the birth year), birthdays aside.