Mayu Kobayashi (Japanese: 小林 茉由; born 10 November 1996) is a Japanese sprinter specializing in the 400 metres.

She was the 2021 Japanese Champion in the 400 m[2] and represented Japan at the 2022 World Athletics Championships.

[3] Kobayashi competed in the women's 4 × 400 m relay and mixed 4 × 400 m relays at the 2021 World Athletics Relays.

[4][5][6] Kobayashi won the 400 m at the 2021 Japan Championships in 53.86.

[2] Kobayashi competed in the mixed 4 × 400 m relays at the 2022 World Championships.