She started in movies at the age of 16 in her native Spain where she filmed her first international success playing an Islamic princess in the 1948 film Locura de amor (where she was credited as María Alejandra), released in the U.S. as The Mad Queen. She derived her stage name from her grandmother (named Sara) and from the Montiel fields of her hometown and was named Sara Montiel from her second film onward. Later she conquered Mexico, starring in a dozen films in less than five years. Hollywood came calling afterwards, and she was introduced to United States moviegoers in the film Vera Cruz (1954) co-starring with Gary Cooper and Burt Lancaster, and directed by Robert Aldrich. She was offered the standard seven-year contract at Columbia Pictures, which she quickly refused, afraid of Hollywood's typecasting policies for Hispanics. Instead she free-lanced at Warner Bros. with Mario Lanza and Joan Fontaine in Serenade (1956), directed by Anthony Mann, and at RKO in Samuel Fuller's Run of the Arrow (1957), opposite Rod Steiger and Charles Bronson.
The unexpected success of the Spanish film El último cuplé (1957) turned her into an overnight sensation both as an actor and a singer. From then on she combined filming highly successful vehicles, recording songs in five languages and performing live all over the world. Among the films that kept her immensely popular during the 1960s and early 1970s were La Violetera (1958), Carmen, la de Ronda (1959), Mi último tango (1960), Pecado de amor (1961), La bella Lola (a 1962 version of Camille), Casablanca, Nid d'espions (1963), Samba (1964), La Femme Perdue (1966), Tuset Street (1967), Esa Mujer (1969), Varietes (1971) and others. In 1974 she announced her retirement from movies but continued performing live, recording and starring on her own variety television shows in Spain. She returned to film with a role in the 2011 film Abrázame.
She was married four times– to American actor and director Anthony Mann, attorney José Vincente Ramírez Olalla, attorney/journalist José Tous Barberán (with whom she adopted her daughter Thaís and her son Zeus), and Cuban camera operator Antonio Hernández.
In 2000, she published her autobiography, Memories: To Live Is A Pleasure, an instant best seller with ten editions to date. A sequel, Sara and Sex, followed in 2003. In these books she revealed other relationships in her past including one-night stands with writer Ernest Hemingway as well as actor James Dean. She also claimed a long term affair in the 1940s with playwright Miguel Mihura and mentioned that science wizard and Nobel Prize winner Severo Ochoa, was the true love of her life.
In 2001, at the age of 73, she received the Rita Moreno HOLA Award for Excellence for the Hispanic Organization of Latin Actors. On 8 April 2013, she passed away at her residence in Madrid, Spain at the age of 85.