How a teenage prodigy rose to become a world Muay Thai champion

Cultures · Published 12 October 2026 · Updated 25 October 2026 Swipe more like this →

In short: At just 17 years and 5 months old, Smilla Sundell achieved what no one else in ONE Championship history had done: winning a world title. From her beginnings in Sweden to the intense training gyms of Thailand, her rapid ascent through the ranks of combat sports is a remarkable story of talent and discipline.

Born in Sundbyberg, Sweden, on 12 November 2004, Smilla Sundell's journey into combat sports began at age five with karate for self-defense. Her focus shifted toward Muay Thai during a vacation in Thailand when she was between 10 and 11 years old. This early exposure led her family to relocate to Ko Samui when she was 12, where she and her sister began training at Yodyut Muay Thai due to a lack of alternative sports options.

Sundell's career reached a historic milestone on 22 April 2022. Competing at ONE 156, she defeated Jackie Buntan to become the inaugural ONE Women's Strawweight Muay Thai World Champion. Aged 17 years and 5 months, she set a record as the organization's youngest world champion. She also secured a $50,000 bonus for Performance of the Night.

Her dominance continued through 2023, including a title defense against Allycia Rodrigues on 29 September 2023, which she won by third-round technical knockout. However, her tenure as champion faced a setback on 4 May 2024 during a title defense against Natalia Diachkova. After weighing in 1.5 pounds over the strawweight limit, Sundell was stripped of her title, though she still won the fight via a second-round technical knockout.

Following her time with ONE, Sundell transitioned to professional mixed martial arts. After signing with the Las Vegas-based promotion Tuff-N-Uff in October 2025, she made her professional MMA debut on 22 January 2026. She secured a first-round technical knockout victory over Miranda Barber, a performance that earned public praise from UFC president Dana White.

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