Ono is regarded as one of judo's top fighters, having won two World Championships and an Olympic gold medal. He has been the lightweight division's most dominant fighter, having remained unbeaten internationally since 2015. Specializing in uchi mata, he is known for his classical technique and all ippon style. He holds one of the highest ippon rates in judo. Ono is also one of the most searched judokas on the Internet.
Ono cemented his place as one of judo's biggest ippon players by winning the prestigious Grand Slam in Tokyo all by ippon. He defeated Lee Shing Him, Yertugan Torenov and Khashbaataryn Tsagaanbaatar in the Round of 32, quarter-final and semi-final by ippon, and Etienne Briand by ippon and two yukos in the Round of 16. He met then reigning world champion and Olympic silver medalist Riki Nakaya in the final. Ono defeated Nakaya with a stunning ippon by osoto gari, adding to a waza-ari he scored earlier on. This would prove to be a turning point in one of the most heated rivalries in the lightweight division, with Ono breaking Nakaya's dominance in the division. The rivalry between the two Japanese fighters would go on for six years.
Ono continued his ippon streak at the Grand Slam in Paris, where he defeated Luiz Alcaraz del Rey and Dirk Van Tichelt by ippon in the Round of 32 and quarter-final, and Ljubisa Kovacevic by ippon and yuko in the Round of 16. His run for a consecutive Grand Slam win ended in the semi-final, where he lost against Tsagaanbaatar by waza-ari. With 30 seconds on the clock, the Mongol threw Ono for waza-ari with Ono's signature uchi mata. The match was already sealed in the former's favour with two shidos against Ono. The Japanese then showed his ippon style again in the bronze medal contest against Benjamin Darbelet with an uchi mata ippon in just eight seconds.
Ono became Japan's third lightweight champion in four years after Hiroyuki Akimoto and Nakaya at the World Championships in Rio de Janeiro. He faced off against Korea's double World Champion Wang Ki-chun in the Round of 64. Fifteen seconds into the fight, Wang attempted a drop morote seoi nage, however was unsuccessful in gaining a score. Ono countered with a juji gatame, but Wang easily escaped by lifting Ono off the ground. Wang then unsuccessfully threw Ono with the latter's single grip on his sleeve with an uchi mata. In a turn of events, Wang was controversially given four shidos to earn a hansoku make or disqualification, namely for three false attacks and breaking off a grip. He unexpectedly crashed out of the tournament in his first fight.
Ono met Neoklis Skouroumounis in his second fight, and scored a yuko early on with de ashi harai. He sealed the fight with ippon with uchi mata. Ono then faced Miklós Ungvári in the Round of 16, who had a similar fate to Wang. Ungvari picked up four shidos for a hansoku make, in the form of avoiding grips, stepping off the mat, attempting a false attack and passivity. Ono went on against Dex Elmont in the quarter-final, in which he again showed his ippon play. Ono scored first with an osoto gari to ushiro goshi for yuko. Elmont then scored a yuko to level the scores. The fight went to golden score with the fighters on equal grounds with a yuko and two shidos each. Ono defeated Elmont with a harai goshi for ippon, and was through to a semi-final against van Tichelt. Ono was ranked number 15, and van Tichelt thirteen places above him. Ono defeated him for a guaranteed medal with one of his best techniques, osoto gari, for ippon.
Ono was set against Ugo Legrand in the final. Ono attempted a double sleeve uchi mata and gained a yuko. Ono won the World title with a strong hane goshi that scored ippon, defeating Legrand. He was overwhelmed with winning the World title and was moved to tears.
Ono also won the Teams' bronze medal with Japan. In the quarter-final he faced Mirali Sharipov, and continued his dominance as a big ippon fighter by defeating the Uzbek with an osoto gari for waza-ari, and uchi mata for ippon.
For me, it's the Ono style of judo. What I wanted to do was demonstrate that the Ono style is the strongest judo style - the number one judo style. That certainly was the goal entering the Olympics.
On May 28, 2013, Ono and four other senior male students in Tenri University’s judo club ordered younger members to slap freshmen in the face. After an investigation, on September 5 Ono was removed from his post of captain of the club and with the other four was suspended for 30 days.
(as of 6 August 2016)