Arnaldo Pomodoro was born on June 23, 1926, in Morciano, Romagna, Italy. He moved to Rimini in 1937, where he studied to become a surveyor. From the mid-1940s until 1957 he served as a consultant for the restoration of public buildings in Pesaro while studying at the Art Institute of in the same city, with a specific interest in stage design and goldsmithery. In 1954 Pomodoro moved to Milan, where he met Enrico Baj, Sergio Dangelo, Lucio Fontana, and other artists. His work was first exhibited that year at the Galleria Numero in Florence and at the Galleria Montenapoleone in Milan. In 1955 his sculptures were shown for the first time at the Galleria del Naviglio in Milan.

He participated together with his brother Giò at the Venice Biennale in 1956, and traveled to Paris, where in 1959 he met Alberto Giacometti. Pomodoro went to the United States for the first time in 1959. Here he organized exhibitions of contemporary Italian art at the Bolles Gallery in New York and San Francisco. In New York the following year Pomodoro met Louise Nevelson and David Smith. He helped found the Continuità group in Italy in 1961–62. The sculptor made his first "sphere" in 1963, and in the same year he was awarded the International Sculpture Prize at the São Paulo Bienal. A solo show of his work was included in the Venice Biennale of 1964. In 1965 he was given the first of many solo exhibitions at the Marlborough galleries in New York and Rome.

The artist taught at Stanford University in California in 1966. In 1967 Pomodoro was represented in the Italian Pavilion at Expo ’67 in Montreal, and he received a prize at the Carnegie International in Pittsburgh. In 1968 he taught at the University of California at Berkeley; he returned in 1970 to attend the opening of an exhibition of his work that later traveled to various cities in the United States. In 1974 a Pomodoro retrospective was sponsored by the City of Milan at the Rotonda della Besana. Since 1990 he is the director of the TAM (Trattamento Artistico Metalli), a school specializing in sculpture, jewellery, and design. Pomodoro’s sculptures were exhibited in the park of the Royal Palace of Caserta in 2000, and his sculpture Novecento, a huge spiral tower, was erected in the Eur district of Rome in 2004. Pomodoro lives and works in Milan.