Jean Fritz was born to American missionaries in Hankow, China, where she lived for the next thirteen years. She was an only child (a sister, Miriam, was born when Jean was 11, but unfortunately Miriam died only a week after her birth). Growing up, Jean kept a journal that she had written about her days in China with Lin Nai-Nari (her amah) and other thoughts such as how she had wanted her name to be Majorie. She moved to the United States with her parents when she was in eighth grade. She graduated in 1937 from Wheaten College. In 1941, she married Michael Fritz. She has two children, David and Andrea, who were both named after friends she had met in Hankow. She currently lives in Dobbs Ferry, New York. To her, writing became a very private place, where no one could come in. She began to form strong emotional bonds to the United States as a young child while still living in China.

Fritz's writing career started with the publication of several short stories in Humpty Dumpty magazine in the early 1950s. In 1954, her first book, Bunny Hopwell's First Spring was published, followed in 1955 by 121 Pudding Street, a work that is said to draw from the lives and characters of her children. She often wrote Westerns or stories of old America because her father would tell her stories of American heroes as she was growing up. Her first historical novel for children is The Cabin Faced West. Eventually she published her autobiography, Homesick, My Own Story in 1982 and won the Newbery Honor citation the following year. Her hard work for children earned her the 1986 Laura Ingalls Wilder Medal.