Mari Yamamoto is a Japanese actress and journalist.

Born in Japan, Yamamoto would move with her family to London in 1991, before eventually returning to live in Tokyo in 1994 at the age of 8. She described the experience as akin to being an outsider, where she'd be considered "very Japanese everywhere in the world" but "wasn’t quite Japanese enough" in Japan itself.

Yamamoto would study international relations at the International Christian University in Tokyo, where she would obtain her Bachelor of Arts, before moving to New York City to study method acting at the Lee Strasberg Theatre and Film Institute. During this time she was also part of The Bats acting company at The Flea Theater. She returned to Tokyo following this, and began working in journalism, writing articles for The Daily Beast alongside American journalist Jake Adelstein. Adelstein's book Tokyo Vice was being adapted into a television series for HBO Max, which would see Yamamoto recruited to work on the show's writing staff. She would become a producer on the series in its second season.

In 2022, Yamamoto starred in a recurring role in the Apple TV+ series Pachinko as Hana. That same year she would join the cast of Apple's Monarch: Legacy of Monsters. In March 2024, she was cast to star opposite Brendan Fraser in the film Rental Family.