Cecchi D'Amico died July 31 in her hometown of Rome, the ANSA news agency said, citing her family. No cause of death was given.
Cecchi D'Amico worked with some of the most renowned Italian directors, including Franco Zeffirelli, Michelangelo Antonioni and Mario Monicelli, whose movie "Casanova 70" earned her an Oscar nomination.
She was equally successful writing scripts for neo-realistic movies, art-house films and comedies such as "Big Deal on Madonna Street." Her work helped make Italy's postwar movie scene vibrant and innovative.
"It was an extraordinary generation, not just for cinema," said longtime friend Monicelli, himself in his 90s.
"That generation grew out of dramatic events such as fascism and war," he said, but "those minds put Italy back on its feet, finding a new way to do things, to produce."
A long partnership with Luchino Visconti became a defining element in Cecchi D'Amico's career, which spanned more than two decades and several movies. Among other titles, she contributed to "The Leopard," the sumptuous depiction of the decline of an aristocratic Sicilian family based on Giuseppe Tomasi di Lampedusa's book and starring Burt Lancaster and Alain Delon.
Born Giovanna Cecchi on July 21, 1914, to a family of writers and intellectuals, she began working in cinema soon after World War II. She quickly landed a high-profile job helping write the script for Vittorio De Sica's "Bicycle Thieves," which was released in 1948 and became a manifesto for neo-realism.
During her long career she often adapted literary works, including "The Stranger," "The Taming of the Shrew" and books by Dostoevsky and Pirandello.
In 1994 the Venice Film Festival awarded Cecchi D'Amico a Golden Lion for lifetime achievement.
Survivors include three children.