She is the reigning Olympic and world champion in women's javelin throw.

Kitaguchi won an individual gold medal at the Youth World Championships[2] and has set Japanese national records in the discipline, throwing 66.00 m at the Honjo Athletic Stadium in Kitakyushu in 2019 and 67.38 m at the Memorial Van Damme event in Brussels in 2023.

At the 2022 World Athletics Championships she won a bronze medal, which made her the first Japanese woman to win a medal in any throwing event at a World Championships or Olympics.

Kitaguchi continued her dominance in the discipline when she claimed gold in the javelin event at the 2024 Summer Olympics in Paris.

In addition to English, Kitaguchi understands and speaks Czech.