Yoshimoto was born in Tokyo on July 24, 1964 and grew up in a liberal family. Her father is the famous poet and critic Takaaki Yoshimoto, and her sister, Haruno Yoiko, is a well-known cartoonist in Japan.
Yoshimoto graduated from Nihon University's Art College with a major in literature. While there, she adopted the pseudonym "Banana", after her love of banana flowers, a name she recognizes as both "cute" and "purposefully androgynous."
Yoshimoto keeps her personal life guarded and reveals little about her certified rolfing practitioner husband, Hiroyoshi Tahata, or son (born in 2003). Each day she takes half an hour to write at her computer, and she says, "I tend to feel guilty because I write these stories almost for fun." Between 2008 and 2010, she maintained an online journal for English speaking fans.
Yoshimoto began her writing career while working as a waitress at a golf club restaurant, in 1987. She named American author Stephen King as one of her first major influences and drew inspiration from his non-horror stories. As her writing progressed, she was further influenced by Truman Capote and Isaac Bashevis Singer.
Her debut work, Kitchen (1988), had over 60 printings in Japan alone. There have been two film adaptations: a Japanese TV movie and a more widely released version titled Wo ai chu fang, produced in Hong Kong by Ho Yim in 1997.
In November 1987, Yoshimoto won the 6th Kaien Newcomers' Literary Prize for Kitchen; in 1988, the novel was nominated for the Mishima Yukio Prize, and in 1999, it received the 39th Recommendation by the Minister of Education for Best Newcomer Artist. In 1988 (January), she also won the 16th Izumi Kyōka Prize for Literature, for the novella Moonlight Shadow, which is included in most editions of Kitchen.
Another one of her novels, Goodbye Tsugumi (1989), received mixed reviews but was made into a 1990 movie directed by Jun Ichikawa.
Her works include 12 novels and seven collections of essays (including Pineapple Pudding and Song From Banana) which have together sold over six million copies worldwide. Her themes include love and friendship, the power of home and family, and the effect of loss on the human spirit.
In 1998, she wrote the foreword to the Italian edition of the book Ryuichi Sakamoto. Conversazioni by musicologist Massimo Milano.
In 2013, Yoshimoto wrote the serialized novel, Shall We Love? (僕たち、恋愛しようか?), for the women's magazine Anan, with singer-actor Lee Seung-gi as the central character. The romance novel was the first of her works to feature a Korean singer as the central character.
Yoshimoto says that her two main themes are “the exhaustion of young Japanese in contemporary Japan” and “the way in which terrible experiences shape a person’s life”.
Her works describe the problems faced by youth, urban existentialism, and teenagers trapped between imagination and reality. They are targeted not only to the young and rebellious, but also to grown-ups who are still young at heart. Banana’s characters, settings, and titles have a modern and American approach, but the core is Japanese. She addresses readers in a very personal and friendly way, with warmth and outright innocence, writing about the simple things such as the squeaking of wooden floors or the pleasant smell of food. Food and dreams are recurring themes in her work which are often associated with memories and emotions. Banana admitted that most of her artistic inspiration derives from her own dreams and that she’d like to always be sleeping and living a life full of dreams.
In August 1988, the Minister of Education awarded Yoshimoto the 39th Best Newcomer Artists Recommended Prize, for Kitchen and Utakata/Sankuchuari. In March 1989, Goodbye Tsugumi was awarded the 2nd Yamamoto Shugoro Prize. In 1994, her first long novel, Amrita, was awarded the Murasaki-shikibu Prize.
Outside Japan, she has been awarded prizes in Italy: the Scanno Literary Prize in 1993, the Fendissime Literary Prize in 1996, the Literary Prize Maschera d' argento in 1999, and the Capri Award in 2011.
The Lake was longlisted for the 2011 Man Asian Literary Prize.