He was the second player in professional baseball to ever win the Triple Crown in three consecutive years, after Korean pitcher Sun Dong-yol.

Yamamoto plays internationally for Japan, winning gold at both the 2020 Summer Olympics in Tokyo and the 2023 World Baseball Classic.

[1] Yamamoto made his Nippon Professional Baseball (NPB) debut on August 20, 2017, three days after his 19th birthday, for the Orix Buffaloes of the Pacific League.

[3] On June 18, 2022, Yamamoto threw the fourth no-hitter in NPB that year, in a 2–0 win over the Saitama Seibu Lions.

[11][12][13] Yamamoto made his major league debut on March 21, 2024 against the San Diego Padres at Gocheok Sky Dome in Seoul, South Korea as part of the MLB World Tour.

[20] He made his playoff debut on October 5, in Game 1 of the National League Division Series, giving up five runs to the Padres in three innings.

[22] He then made one start, in Game 4, in the National League Championship Series, allowing two runs on four hits in 4+1⁄3 innings, while striking out eight batters.

[24] Yamamoto has represented Japan in international tournaments, including the 2019 WBSC Premier12,[25][26] the 2020 Summer Olympics, and the 2023 World Baseball Classic (WBC).

In the Olympics, Yamamoto pitched in two games, allowing two runs and striking out 18 batters in 11+2⁄3 innings as Japan won gold in Tokyo.