Over the course of her career, Cortese worked with many important Italian and international directors, including Michelangelo Antonioni, Federico Fellini, Franco Zeffirelli, François Truffaut, Joseph L. Mankiewicz and Terry Gilliam.

[3][4][5] After meeting conductor Victor de Sabata, then married with children and 31 years her senior, she quit high school and followed him to Rome, where she enrolled at (and later graduated from) the National Academy of Dramatic Arts (Accademia d'arte drammatica).

[3] Cortese continued to appear in national and international productions; the most notable of this era include Joseph Mankiewicz's The Barefoot Contessa (1954) and Michelangelo Antonioni's Le Amiche (1955).

[3] In the following years, she worked for directors as diverse as Mario Bava (The Girl Who Knew Too Much, 1963), Bernhard Wicki (The Visit, 1964), Federico Fellini (Juliet of the Spirits, 1965), Robert Aldrich (The Legend of Lylah Clare, 1968) and Joseph Losey (The Assassination of Trotsky, 1972).

[15] While her later films were mostly of lesser artistic interest, Cortese was continuously successful on stage,[3] working with Giorgio Strehler, with whom she had a long-lasting relationship,[3][4] Franco Zeffirelli,[3][4] Luchino Visconti[3] and Patrice Chéreau.