The oldest of three children, Caracciolo was born in Florence to Filippo Caracciolo, 8th Principe di Castagneto, 3rd Duca di Melito and American heiress Margaret Clarke. He was an older brother to Marella Agnelli, the wife of Fiat chairman Gianni Agnelli and half-sibling of film producer Ettore Rosboch von Wolkenstein (whose daughter Bloomberg journalist Elisabetta "Lili", Carlo's goddaughter, married Prince Amedeo of Belgium, Archduke of Austria-Este). At 18, he fought in the Italian resistance in World War II. After the war he attended Harvard Law School and worked for a New York law firm that had as a partner Allen Dulles, future head of the CIA. In the United States he began to show a serious interest in publishing.
In 1951, he moved into publishing in Milan, and in 1955 set up the N.E.R. (Nuove Edizioni Romane) publishing house with the progressive industrialist Adriano Olivetti, manufacturer of Olivetti typewriters. In October 1955 the company founded the news magazine L'Espresso with editors Arrigo Benedetti and Eugenio Scalfari.
Caracciolo was a man of the liberal left. He disdained his aristocratic title, but betrayed it in his elegance of dress and manner. He believed that a modern postwar Italian republic should be run on lay rather than religious principles, and his news outlets campaigned for reform of the laws governing divorce and abortion.
L'Espresso was characterized from the beginning by an aggressive investigative journalism strongly focussed on corruption and clientelism by the Christian Democrat party. This made the main shareholder Olivetti unpopular with the ministries and large companies that were the primary customers of his main business. In 1956, with the magazine losing money, Olivetti made Caracciolo a present of the majority shareholding.
In 1976 he and Eugenio Scalfari, with backing from the publisher Arnoldo Mondadori Editore, set up the daily newspaper La Repubblica. Founded in Rome as a national newspaper and published in the novel tabloid size.
In 1984, shortly before it began to outsell the prestigious Corriere della Sera, Caracciolo took his publishing activities to the Italian stock exchange. Four years later he sold his holdings in Editoriale L'Espresso to Mondadori. In 1990, however, he was shocked to learn that Mondadori’s heirs had sold out to Silvio Berlusconi, whose politics he detested. After much in-fighting and litigation, the news publications were hived off into the Gruppo Editoriale L'Espresso controlled by the CIR Group of entrepreneur Carlo De Benedetti, of which Caracciolo remained honorary president until 2006.
In 2007, a year after he retired from the Espresso Group to become its honorary chairman, he bought a 33 percent share in the French newspaper Libération.
He died in Rome, aged 83. According to his biographer and former co-editor of L'Espresso, Nello Ajello : "He set an example for free and independent editorial content that initially seemed marginal and exclusive and instead became a major force in Italian newspaper publishing".
In June 1989, he was awarded the Italian Order of Merit for Labour.