Niki de Saint Phalle was born in France in 1930 by the name Catherine Marie-Agnes Fal de Saint Phalle. At age 3, her family moved to the United States. She would spend her childhood and adolescence in New York. As a young adult, she embarked on a flourishing modelling career and made covers for Vogue and Life Magazine.

At the age of 18, she fled to marry writer Harry Mathews, a childhood friend. The couple moved to Europe in the 1950s to live and work there. They mainly lived in Paris. Two children born of this union: Laura, en 1951, et Phillip, en 1955. In 1953, after being hospitalised for a nervous breakdown, Niki de Saint Phalle began painting. This form of therapy would help her overcome the ordeal. It is at this turning point that she decided to become an artist.

In 1960, she separated from Harry Mathews to pursue an artistic career, leaving him in care of their two children. She rented a studio on the Impasse Ronsin passageway in Paris, where she would surround herself with other artists including Jean Tinguely, who would become the faithful collaborator she would go on to marry in a second marriage. The only woman in the avant-garde New Realist group, she rubbed shoulders with the big names of the time, including Jasper Johns and Robert Rauschenberg. The works of Niki de Saint Phalle appeared on the walls of major exhibitions at the City of Paris Museum of Modern Art in 1960 and in The Art of Assemblage at the Museum of Modern Art in New York in 1961.

In the mid-1960s, she embarked on the creation of her now iconic works, "Les Nanas". In 1966, Niki collaborated with Jean Tinguely and Per Olof Ultvel to develop Hon (She in Swedish) for the Moderna Museet of Stockholm. Her work, a lying monumental Nana, occupies the entire exhibition hall. Visitors can enter and walk around. It was at this time that she made her first outdoor sculptures, such as Le Paradis Fantastique (with Tinguely) for the Pavillon Français at the 1967 World Expo in Montreal. In the 1970s, she was solicited for many architectural projects around the world, including Le Golem in Jerusalem (1972) and Le Dragon de Knokke (1973–75) in Belgium. In 1975, on the occasion of an arts festival, the Palais des Beaux-Arts in Brussels hung its monumental piece Last Night I Had a Dream to its facade.

In the mid-1970s, a childhood friend offered Niki de Saint Phalle a plot in Tuscany where she finally realised her dream of creating a garden of monumental sculptures: Le Jardin des Tarots. Work began in 1980. Over the next ten years, Niki de Saint Phalle would work on the project with the help of friends and colleagues. In 1982, she moved to L’Impératrice, a building shaped like a sphinx that served as a workshop and home. She created a series of clean sculptures called The Skinnies, which were regarded as linear drawing-sculptures in space. Le Jardin des Tarots would finally open to the public in 1998.

In 1980, the National Museum of Modern Art at the Georges Pompidou Centre in Paris devoted a major retrospective to her that travelled throughout Europe. In 1982, she worked with Jean Tinguely on the Stravinsky Fountain on the esplanade of the Georges Pompidou Centre in Paris, in homage to the composer Igor Stravinsky. It was at this time that she began to suffer from the first recurrent and disabling attacks of rheumatoid arthritis.

In the mid-1990s, she moved to La Jolla (California) for health reasons, but she continued to accept many public commissions worldwide. In 2000, she directed Queen Califia’s Magical Circle in Escondido (California). This would be her last major project. Niki passed away in 2002 at the age of 71 in La Jolla (California).