Yamamoto started skating when he was five. He is a 3-time Japanese national novice medalist. He was invited to skate in the gala at the 2013 World Team Trophy as the Japanese national novice champion in the same season.
During the 2014–15 JGP series, Yamamoto won silver medals in Courchevel, France and Tallinn, Estonia, which qualified him to the 2014–15 JGP Final in Barcelona, Spain. Ranked first in the short program and third in the free skate, he finished second overall, behind Shoma Uno and ahead of Alexander Petrov. Nationally, he was the junior silver medalist, behind Shoma Uno, and finished 6th at the senior event. At the 2015 World Junior Championships, Yamamoto placed 7th in the short program and 3rd in the free skate to win the bronze medal in his first appearance at that competition.
After missing the entirety of the 2016–2017 season, Yamamoto returned to competition domestically at the 2017–18 Japan Championships, placing ninth. Venturing out internationally, he placed fifth at the Coupe du Printemps.
Again beginning the season with two Challenger assignments, Yamamoto won the silver medal at the 2019 CS U.S. Classic after placing third in the short program and second in the free skate. the season at the 2019 CS Finlandia Trophy, and led the field after the short program, in which he set a new personal best and landed two quad jumps. He fell four times in the free skate, placing sixth in the segment, but narrowly took the silver medal overall.[4]
2020–21 season
Yamamoto won the gold medal at the domestic Western Sectionals championship, qualifying for a berth to the national championships.[5] Assigned to the 2020 NHK Trophy, he placed eighth.[6] He was ninth at the 2020–21 Japan Championships.
Beginning the season on the Grand Prix, Yamamoto won the short program at the 2022 Grand Prix de France. He was overtaken in the free skate by Frenchman Adam Siao Him Fa, but still scored a new personal best in that segment and won the silver medal, his first Grand Prix podium placement. Yamamoto reflected on his past struggles with injury, saying that it made the moment "special for me, and I know I couldn't have achieved it myself. I have had all the support from my team as well as support from the fans."[11] At his second event, the 2022 NHK Trophy on home ice in Sapporo, Yamamoto again finished first in the short program with a new personal best score of 96.49, ahead of reigning World championShoma Uno.[12] He was again overtaken in the free skate, this time by Uno, but won his second silver medal and qualified to the Grand Prix Final for the first time. He said that he was pleased at the prospect of competing together with Uno at the Final.[13][14]
At the Final in Turin, Yamamoto finished second in the short program behind Uno. He assessed that his quad Salchow was "not perfect, but I am happy I was able to skate without any mistakes and going into the free skating, it will be a confidence boost." The segment also saw several other skaters, such as widely favoured American Ilia Malinin, underperform.[15][16] In the free skate, Yamamoto set a new personal best (on his way to a personal best total score as well), finishing third in the segment behind Uno and Malinin, but remaining second overall. Winning the silver medal, he said he was pleased to have delivered a satisfactory free skate for the first time in the season and to have achieved his goal of making the podium.[17][18]
Yamamoto finished third in the short program at the 2022–23 Japan Championships, but a seventh-place free skate dropped him to fifth overall.[19][20] Despite this, due to the Japan Skating Federation's selection criteria incorporating international results, he was selected as Japan's third man for the 2023 World Championships, which occasioned some controversy due to national silver medalist Koshiro Shimada being passed over.[21]
Yamamoto began the season at the 2023 CS Autumn Classic International, finishing in fourth place.[9] Moving on to the Grand Prix, he started at the 2023 Skate Canada International. First in the short program despite an underrotated quad jump and a spin error, he was only third in the free skate, but remained in first place overall to claim his first Grand Prix gold medal.[25] At the 2023 Cup of China, he finished in sixth place after struggles in the short program.[26]
At the 2023–24 Japan Championships, Yamamoto finished second in the short program, albeit more than ten points behind segment leader Shoma Uno.[27] In the free skate he came third, and placed third overall, winning the bronze medal and standing on the Japanese national podium for the first time in his senior career. Reflecting on his career, Yamamoto said there "were good times and bad times, and there were really tough days. But I'm glad I did my best even through those times. This is the result I was aiming for, but I want to look even further ahead, set my goals even higher, and grow even more."[28]
^"山本が世界ジュニア欠場 練習中に右足首骨折/フィギュア" [Yamamoto fractures right ankle in practice, will miss Junior Worlds] (in Japanese). Sanspo. 10 March 2016. Archived from the original on 12 March 2016.