Smilla Sundell

Smilla Sundell profile

Smilla Sundell became the youngest world champion in ONE Championship history at 17 years and 5 months. Born in Sundbyberg, Sweden on 12 November 2004, she stayed in Thailand alone at 15 to keep fighting, and is now rebuilding her career in MMA in Las Vegas.

Staying in Thailand alone at fifteen

Sundell started karate at five and first tried Muay Thai on a family holiday in Thailand at around ten. Her family moved to Ko Samui when she was twelve, and she and her younger sister began training at Yodyut Muay Thai because there was little else on the island.

Three years later her family moved back to Sweden. She asked to stay behind on her own to keep fighting, and when she ran out of opponents on Samui she moved to Pattaya in October 2019 to join Fairtex Gym, after watching Stamp Fairtex fight.

Youngest champion in the promotion's history

She signed with ONE in 2021 at 31-5-1, debuted in February 2022 with a third-round TKO of Diandra Martin in her first fight in four-ounce gloves, and two months later beat Jackie Buntan by unanimous decision at ONE 156 for the inaugural women's strawweight Muay Thai world title.

At 17 years and 5 months she was the youngest world champion in ONE history, and the win carried a $50,000 Performance of the Night bonus. She was named ONE Super Series Female Fighter of the Year for 2022.

The weight problem

She defended the belt once, stopping atomweight champion Allycia Hellen Rodrigues in the third round on 29 September 2023 for a second $50,000 bonus.

On 4 May 2024 she weighed in 1.5 pounds over the strawweight title limit and was stripped before the fight with Natalia Diachkova, which she still won by second-round TKO. In August 2025 she was removed from the ONE roster because her weight had passed the promotion's heaviest women's division.

Starting again in a cage

She signed with Las Vegas promotion Tuff-N-Uff in October 2025 and won her professional MMA debut on 22 January 2026, stopping Miranda Barber with knees and elbows in the first round.

A second-round TKO of Maya Stewart on 5 June 2026 took her to 2-0, and she is scheduled to appear on Dana White's Contender Series season 10 on 13 October 2026.

Record

Scope: Professional Muay Thai and kickboxing · last verified 25 September 2026