[5] Sakamoto began learning to skate on November 18, 2003, in Kobe and has been with her coaches Sonoko Nakano, Mitsuko Graham, and Sei Kawahara since starting.

During the 2013–2014 season, Sakamoto debuted on the ISU Junior Grand Prix (JGP) circuit, placing sixth in Ostrava, Czech Republic.

Sakamoto received medals at both of her 2016–17 JGP assignments – silver in France and gold in Japan[8] – and then won the Japanese junior title.

In December, she took the bronze medal at the Junior Grand Prix Final in Marseille, France, and placed seventh, competing on the senior level at the Japan Championships.

Making her senior Grand Prix debut, she finished 5th at the 2017 Rostelecom Cup after placing fourth in the short program and fifth in the free skate.

Sakamoto began the season at the 2018 CS Lombardia Trophy, where a disastrous short program left her in ninth place going into the free skate.

"[14] At the 2018–19 Grand Prix Final, Sakamoto placed fourth in both segments, narrowly missing the podium after falling on the last part of her three-jump combination.

[22][23] Her second Grand-Prix event was the 2019 Internationaux de France, where she placed sixth in the short program after falling on a double Axel and putting a foot down on her triple loop.

[25] On the 2019–20 Japanese Championships, Sakamoto was third in the short program despite underrotating the back half of her jump combination and was narrowly behind second-place Satoko Miyahara.

[33][34] At the 2020–21 Japan Championships, Sakamoto entered with the perceived momentum from her NHK Trophy win but faced the returning Rika Kihira, who had been scheduled to compete elsewhere on the Grand Prix that season.

[35] Sakamoto made an error in her short program, performing only a double toe loop instead of a planned triple as part of her jump combination, but ended up in second place, 7.48 points behind Kihira.

She was third in the free skate with no issues other than an edge call on her triple Lutz, but remained in fourth place overall, 1.04 points behind bronze medalist You Young.

[46][47] Sakamoto's second assignment was Japan's home event 2021 NHK Trophy, which she entered as the frontrunner due to injury-related withdrawals from both Alexandra Trusova and Daria Usacheva.

[48][49] Sakamoto's results qualified her to the Grand Prix Final, but it was subsequently cancelled due to restrictions prompted by the Omicron variant.

She skated cleanly to win both segments of the competition and her second gold medal, 12.28 points ahead of silver medalist Wakaba Higuchi.

[52] In the women's event, Sakamoto skated a clean short program and earned a new personal best of 79.84, ranking third in the segment behind Valieva and Anna Shcherbakova.

[53] Despite placing third in the short program, it was widely assumed going into the free skate that Sakamoto would be passed by Alexandra Trusova, in fourth, whose technical content greatly exceeded hers.

[56] Skating cleanly, she won the short program with a new personal best score of 80.32, 5.32 points clear of second-place Loena Hendrickx of Belgium.

[57] She went on to win the free skate as well, setting new personal bests in that segment (155.77) and total score (236.09), the latter nearly twenty points clear of silver medalist Hendrickx.

Narrowly first in the short program after performing only a triple-double combination, she won the free skate decisively over American Isabeau Levito to take the gold medal, a result she said left her "filled with joy.

'"[65] Sakamoto entered the Final as a contender for the title, winning the short program by 1.28 points over longtime friend and training partner Mai Mihara.

[70] Her free skate score, 155.26, was a new domestic personal best, earning her the national title for the second consecutive year, ahead of Mihara and bronze medalist Mao Shimada.

[73] At the 2023 World Championships in Saitama, Sakamoto won the short program with a score of 79.24, more than five points clear of South Korea's Lee Hae-in in second place.

[75] In doing so, Sakamoto became the fourth woman to win consecutive World Championships since abolition of compulsory figures in 1991, after Kristi Yamaguchi (1991-1992), Michelle Kwan (2000-2001), and Evgenia Medvedeva (2016-2017).

[81] In preparation for the 2023–24 figure skating season, Sakamoto worked with choreographer Jeffrey Buttle on her short program, having selected the music "Baby, God Bless You" from the soundtrack of Japanese medical drama, Kōnodori.

[85] Sakamoto began the Grand Prix with her first-ever appearance at the Skate Canada International, winning both segments of the competition to take the gold medal by a 25-point margin over silver medalist Kim Chae-yeon of South Korea.

[91] At the 2024 World Championships in Montreal, Sakamoto placed fourth in the short program after a somewhat shaky performance that saw a rough landing on her triple Lutz and a stumble in her step sequence.

[94] Sakamoto began the season by finishing third at the 2024 CS Lombardia Trophy behind American skaters, Amber Glenn and Sarah Everhardt.

"[96] Two weeks later, at the 2024 NHK Trophy, Sakamoto delivered two clean performances and won the event, almost twenty points ahead of silver medalist Mone Chiba.

[101] In the free skate, she received under-rotation calls on her jump combinations in the second half of the program but rose to third place overall to win the bronze medal.