Madeleine L'Engle Camp was born in New York City and educated in boarding schools in Switzerland and across the United States. A shy, withdrawn child with few friends, she retreated into writing at an early age. She attended Smith College, graduating summa cum laude in 1941. After college, she worked in the New York theatre, where she met her future husband, Hugh Franklin. (Later she would say that they "met in The Cherry Orchard and married during The Joyous Season.") Her first book, The Small Rain (1945), was completed while she was still working as an actress.

After the birth of their first child, Madeleine and her husband moved to rural Connecticut to run a small general store; but in 1959, they returned to New York City with their three children so Hugh Franklin could resume his acting career (For many years, he played Dr. Charles Tyler on the popular television soap opera All My Children.) Although Madeleine wrote steadily during this period, few of her books were published. Then, in 1960, she released her first children's story, Meet the Austins. An affectionate portrait of a close-knit family, the book was named an ALA Notable Children's Book of the year and spawned several bestselling sequels.

Completed in 1960, L'Engle's science fiction YA classic A Wrinkle in Time was rejected by more than two dozen publishers before Farrar, Straus and Giroux finally released it in 1962. Elegant, imaginative, and filled with complex moral themes, the acclaimed Newbery Medal winner tells the story of Meg Murry, a young girl who travels through time with her psychically gifted younger brother to rescue their scientist father from a planet controlled by an evil entity known as the Dark Thing. Throughout her career, L'Engle would return to the Murry family three more times, in A Wind in the Door (1973), A Swiftly Tilting Planet (1978), and Many Waters (1986). The Time Quartet, as these four books have come to be called, weaves together elements of theology and quantum physics often assumed to be far too esoteric for children to understand. Yet, it became a true classic of juvenalia. L'Engle explained once, "You have to write the book that wants to be written. And if the book will be too difficult for grown-ups, then you write it for children."

In addition to her YA novels, the prolific writer also penned adult fiction, poems, plays, memoirs, and religious meditations. She served as the longtime librarian and writer-in-residence for the Cathedral Church of St. John the Divine. Madeleine L'Engle passed away at a nursing home in Connecticut in 2007.