Catherine Marie-Agnès Fal de Saint Phalle was born on October 29, 1930 in Neuilly-sur-Seine, Hauts-de-Seine, near Paris. Her father was Count André-Marie Fal de Saint Phalle (1906–1967), a French banker, and her mother was an American, named Jeanne Jacqueline Harper (1908–1980).
At eighteen, Saint Phalle eloped with author Harry Mathews, whom she had known since the age of twelve through her father, and moved to Cambridge, Massachusetts. While her husband studied music at Harvard University, Saint Phalle began to paint, experimenting with different media and styles. Their first child Laura was born in April 1951.
Saint Phalle rejected the staid, conservative values of her family, which dictated domestic positions for wives and particular rules of conduct. Poet John Ashbery recalled that Saint Phalle's artistic pursuits were rejected by members of Saint Phalle clan: her uncle "French banker Count Alexandre de Saint-Phalle, reportedly takes a dim view of her artistic activities" Ashbery observed. However, after marrying young and becoming a mother, she found herself living the same bourgeois lifestyle that she had attempted to reject; the internal conflict, as well as reminiscences of her rape by her father when she was only 11 caused her to suffer a nervous breakdown. As a form of therapy, she was urged to pursue her painting.
While in Paris on a modeling assignment, Saint Phalle was introduced to the American painter Hugh Weiss, who became both her friend and mentor. He encouraged her to continue painting in her self-taught style. She subsequently moved to Deià, Majorca, Spain, where her son, Philip Abdi, was born in May 1955. While in Spain, Saint Phalle read the works of Proust and visited Madrid and Barcelona, where she became deeply affected by the work of Antoni Gaudí. Gaudí's influence opened many previously unimagined possibilities for Saint Phalle, especially with regard to the use of unusual materials and objets-trouvés as structural elements in sculpture and architecture. Saint Phalle was particularly struck by Gaudí's "Park Güell" which persuaded her to create one day her own garden-based artwork that would combine both artistic and natural elements.
Saint Phalle continued to paint, particularly after she and her family moved to Paris in the mid-1950s. Her first art exhibition was held in 1956 in Switzerland, where she displayed her naïve style of oil painting. She then took up collage work that often featured images of the instruments of violence, such as guns and knives.
In 1966, Saint Phalle collaborated with fellow artist Jean Tinguely and Per Olof Ultvedt (sv) on a large-scale sculpture installation, "hon-en katedral" ("she-a cathedral") for Moderna Museet, Stockholm, Sweden. The outer form of "hon" is a giant, reclining 'Nana', whose internal environment is entered from between her legs. The piece elicited immense public reaction in magazines and newspapers throughout the world. The interactive quality of the "hon" combined with a continued fascination with fantastic types of architecture intensified her resolve to see her own architectural dreams realized. During the construction of the "hon-en katedral," she met Swiss artist Rico Weber, who became an important assistant and collaborator for both de Saint Phalle and Jean Tinguely. During the 1960s, she also designed decors and costumes for two theatrical productions: a ballet by Roland Petit, and an adaptation of the Aristophanes play "Lysistrata." In 1971 Saint Phalle and Tinguely married. Saint Phalle moved to California in 1994.
On 17 November 2000 she became an honorary citizen of Hannover, Germany, and donated 300 pieces of her artwork to the Sprengel Museum. In 2000 the artist was awarded with the Praemium Imperiale award for Sculpture by the Japan Art Society. In 2001, she made another donation of 170 pieces to the Musée d'art moderne et d'art contemporain of Nice.
Saint Phalle died of emphysema in California on 21 May 2002.