Mari Yamamoto is a Japanese actress and journalist.

Born in Japan, Yamamoto moved with her family to London in 1991, then returned to live in Tokyo in 1994 at the age of 8. She described this experience as feeling like an outsider, being considered "very Japanese everywhere in the world" but "not Japanese enough" in Japan itself.

Yamamoto studied international relations at International Christian University in Tokyo, where she earned a Bachelor of Arts degree, and then moved to New York to study method acting at the Lee Strasberg Theatre and Film Institute. During this time she was also part of the acting company The Bats at The Flea Theater. After that she returned to Tokyo and began working in journalism, writing articles for The Daily Beast together with American journalist Jake Adelstein. Adelstein's book "Tokyo Vice" was adapted into a television series for HBO Max, and Yamamoto was brought on to work in the show's writing group. In the second season of the series she became a producer.

In 2022 Yamamoto played the recurring role of Hana in the Apple TV+ series "Pachinko." That same year she joined the cast of the Apple series "Monarch: Legacy of Monsters." In March 2024 she was cast in the lead role alongside Brendan Fraser in the film "Rental Family."