Japan gets first sumo champion in 19 years
He is the first Japanese-born wrestler to make it since Wakanohana in 1998. Five wrestlers from American Samoa and Mongolia have made it in the interim.
Foreign wrestlers have come to dominate sumo, amid a lack of local recruits.
Kisenosato, who comes from Ibaraki to the north of Tokyo and weighs 178kg (392 pounds), has been an ozeki - the second-highest rank - since 2012.
After being runner-up on multiple occasions, he finally clinched his first tournament victory - and thereby his promotion to yokozuna - in the first competition of 2017.
"I accept with all humility," Kisenosato said in a press conference after the Japan Sumo Association formally approved him.
"I will devote myself to the role and try not to disgrace the title of yokozuna."