The company was founded in 1932 through a merger of the Genoa-based Navigazione Generale Italiana (NGI), the Turin-based Lloyd Sabaudo, and the Trieste-based Cosulich STN lines, encouraged by the Italian government.

The same year two previously ordered ocean liners were delivered to the company: Rex, that won the Blue Riband in 1933, and Conte di Savoia.

In 1956, Andrea Doria, the company's three-year-old flagship collided with the Swedish ship Stockholm near Nantucket and sank, with passenger deaths estimated at 46 or 55.

Despite huge financial loss, the Italian Line operated the transatlantic route until 1976, after which the Leonardo da Vinci was withdrawn from service; the Michelangelo and Raffaello had been sold the previous year.

In 1979 and 1980 the company operated two ex-Lloyd Triestino liners, Galileo Galilei and Guglielmo Marconi, as cruise ships, but this again proved unprofitable.