[1] Born Aiko Araki in Tokyo, Miyawaki moved to Atami, Shizuoka Prefecture with her family at a young age.

At Japan Women’s University, she studied with historian Noboru Ōrui in the Department of History and her thesis focused on the art of the Momoyama period.

[2] Also through Kamiya, Miyawaki was introduced to the artist Yoshishige Saitō, and this encounter made her realize the significance of exhibiting her works.

[1] Meanwhile, having wanted to know more about art overseas, Miyawaki went to the U.S. for a short time to study painting at the University of California, Los Angeles and Santa Monica City College in 1957.

[2][4] Around 1959, Miyawaki developed a new and innovative series by mixing enamel and marble powder with paint and applying it directly on canvas often with a palette knife to create textured and sometimes patterned surfaces.

Miyawaki started to create works using brass pipes, square tubes and cylinders to manifest the effect of light.

[1] Miyawaki recalled that in the creation of these works, she had students from the Department of Architecture at the University of Tokyo helping her in her studio by performing such tasks as polishing the pipes.

[2] In November 1966, Miyawaki participated in the exhibition From Space to Environment, held at the Matsuya department store in Ginza, Tokyo, where she first met the architect and designer Arata Isozaki.

For example, in the MEGU series, each work consisted of a stack of glasses that are collected broken, as opposed to having been manually cut which would not result in the transparency of the entire sculpture that she had planned for.

For that project, she experimented with the idea of expressing the free spirit, or "qi (chi)" in Chinese, as if drawing lines in the void.

[1] In 1978, Miyawaki participated in the exhibition MA—Espace/ Temps au Japon (「日本の時空間―<間>」) at the Musée des Arts Décoratifs in the Palais du Louvre, which was organized by Isozaki.

[1][12] In March 1980, UTSUROI, the first work of Miyawaki's signature Utsurohi series was installed in Hikoda Children's Park in Ichinomiya, Aichi Prefecture.

[1][14][15] In 1990, Utsurohi was installed in the square in front of the Sant Jordi Sports Palace, which was designed by Isozaki for the Barcelona Olympics in 1992.

In 1994, together with Shūsaku Arakawa and Kazuro Okazaki, Miyawaki installed the work at the Isozaki-designed Nagi Museum of Contemporary Art in Okayama.

[17][18] In 2023 her work was included in the exhibition Action, Gesture, Paint: Women Artists and Global Abstraction 1940-1970 at the Whitechapel Gallery in London.