Born in 1928, Kochi Prefecture, Okanoue was raised in Tokyo. She was studying fashion design in Bunka Gakuin when she first started making photo collages in class. She playfully cut out various image fragments from pictorial and fashion magazines like LIFE, VOGUE and Harper's Bazaar and combine different faces, body parts and animals together.

Although her works were discovered by famous surrealist artist and critic Shuzo Takiguchi and well acclaimed by the public, her collage production ended 6 years after she started from when she was 22 years old. However in 1996 her works were displayed in Meguro Museum of Art and her solo exhibition, namely, "Toshiko Okanoue's Photo Collages: Droplets of Dreams" was held in Dai-ichi Mutual Life Insurance Co. South Gallery. Her monograph "Drop of Dreams: Toshiko Okanoue: Works 1950-1956" was publicized by Nazraeli Press in 2002. Okanoue's works were collected by the Museum of Fine Arts, Houston in 2003, then later followed by the Museum of Modern Arts, New York in 2010, which made her works come under the spotlight of attention, once again after half a century. In Spring 2015, Okanoue's first monograph "A LONG JOURNEY" was released in Japan.