Joo Sang Yoo Record: 9-1-0

Regional rise and the marquee win

The turning point in Yoo's pre-UFC run was a December 2022 unanimous-decision victory over grizzled Japanese veteran Shunichi Shimizu at AFC 22, a result that showcased his composure against an opponent with more than 70 pro fights of experience. He carried that momentum forward with first-round stoppages of Takuya Kuramoto and Masuto Kawana, the latter a clean knockout that helped seal his ticket to the big show.

UFC debut and a brutal lesson

Yoo announced himself in spectacular fashion at UFC 316 in June 2025, starching Indonesian striker Jeka Saragih with a perfectly timed counter left hook just seconds into the first round — one of the most violent debut knockouts of the year. The reality check came quickly. At UFC 320 in October 2025, Yoo ran into Daniel Santos, who handed him the first loss of his career via second-round TKO. It was a chastening result, but one that arrived against a sharp, experienced opponent at the sport's highest level.

Fighting style

Yoo is a pressure-minded knockout artist whose calling card is concussive punching power. His finish breakdown tells the story: four of his nine wins have come by KO or TKO and one by submission, a 56% finish rate, with his decision victories underlining that he can also grind out rounds when the stoppage isn't there. His counter left hook is a genuine fight-ender, as the Saragih knockout proved, and he pairs it with a willingness to trade in the pocket. The Santos loss exposed the flip side of that aggression: at UFC level, hittable exchanges carry steep consequences, and rounding out his defensive layers will define how high his ceiling climbs.

Career highlights

• Viral UFC debut knockout — flattened Jeka Saragih with a one-punch counter at UFC 316, one of 2025's best finishes.
• Undefeated regional run — went 9–0 before the UFC, capturing featherweight titles and beating veteran Shunichi Shimizu along the way.
• The Korean Zombie connection — carries Chan Sung Jung's legacy as "Zombie Jr.," reaching the UFC through a finish at his idol's event.