Born on July 30, 2004, in Taipei, Taiwan, Jozef Chen grew up in a multicultural household with a Taiwanese father and a German-South African mother. His early years were marked by frequent relocations across major Asian cities, including Kuala Lumpur, Doha, Beijing, Guangzhou, Nanjing, and Shanghai. Initially excelling in track and field as well as swimming, Chen discovered martial arts at age 13, first training Muay Thai in Nanjing, China, before transitioning to Brazilian Jiu-Jitsu.

Chen began his Brazilian Jiu-Jitsu journey in August 2018 under coach Guillaume Leclerc in China. Due to limited training resources at his gym, he developed a unique, self-directed learning approach. Rather than passively watching entire instructional series, Chen meticulously studied short video clips, extracting key technical details and immediately applying them during live sparring sessions. This disciplined, analytical practice enabled him to rapidly master modern leg lock systems and wrestling sequences, significantly accelerating his technical progression.

Within approximately five years of starting Brazilian Jiu-Jitsu, Chen reached an elite competitive level. His breakthrough occurred at the 2023 ADCC European Trials, where he dominated a highly competitive bracket to secure qualification for the prestigious ADCC World Championships. Prior to this achievement, Chen had already showcased his rapid improvement by earning a medal at the 2022 ADCC Asia & Oceania Trials. His swift ascent has firmly established him as one of the most promising young talents in no-gi submission grappling.

In 2022, Chen traveled to Austin, Texas, to train at B-Team Jiu-Jitsu under renowned grapplers Craig Jones and Nicky Ryan. His impressive development led to his promotion to brown belt by Craig Jones in 2023, followed by his black belt promotion in mid-2024 at the age of 20. Chen's grappling style clearly reflects the B-Team's influence, emphasizing sophisticated leg entanglements, dynamic wrestling scrambles, and confident guard play. Despite his affiliation with B-Team, Chen maintains strong connections with his original coaches and training partners internationally, crediting their open-minded environment as instrumental to his early success.

Following his victory at the 2023 ADCC European Trials, Chen signed with ONE Championship in 2024 to compete in their submission grappling events. His professional debut featured a high-profile match against reigning ADCC champion Tye Ruotolo. Although Chen lost by decision, his technical skill, strategic composure, and resilience earned widespread praise. Competing on the ONE Championship platform has positioned Chen as one of the youngest professional grapplers on a major international promotion, significantly expanding his personal brand and following, particularly in Asia.

Chen is widely recognized within the grappling community for his humble demeanor, analytical mindset, and mature approach to competition. Frequently observed at tournaments quietly studying adult black belt matches and meticulously taking notes, he exemplifies a dedicated student-of-the-game mentality. Chen has openly expressed his ambition to become "the coach I never had," indicating future plans to establish an academy or mentorship program. He actively contributes to the global grappling community by sharing detailed breakdowns of his competition footage on social media, providing valuable insights into his techniques and strategic thinking.

Chen's grappling style is characterized by a sophisticated integration of modern leg lock systems, wrestling sequences, and dynamic guard play. His methodical approach involves systematically implementing studied techniques, reflecting his disciplined training methodology. Due to his diverse international training experiences, Chen quickly adapts to various grappling styles and continuously refines his game by identifying and addressing specific technical gaps after competitions. This analytical approach ensures ongoing improvement and positions him as a formidable competitor on the international stage.