ONE Samurai 4 was a kickboxing, Muay Thai, and MMA event held by ONE Championship on Saturday, October 17, 2026, at Ariake Arena in Tokyo, Japan. In the main event, Jonathan Haggerty faced Hiroki Akimoto for the ONE Bantamweight Kickboxing World Championship, while Nadaka Yoshinari took on Rifdean Masdor for the Atomweight Muay Thai World Championship in the co-main event. The card also featured Masaaki Noiri vs. Mohammad Siasarani, Marat Grigorian vs. Luo Chao, and Rukiya Anpo vs. Bogdan Shumarov, and the event doubled as the night ONE Championship inducted Takeru Segawa into its Hall of Fame.
