He was born in Morciano di Romagna on 23 June 1926. After only a few months the family moved to Orciano di Pesaro, in the Marche region, where Arnaldo spent his childhood. In 1937 he moved to Rimini to continue his studies: he attended middle school and then the technical institute for surveyors. At the outbreak of the Second World War he returns to Orciano.

He is passionate about reading Italian and foreign contemporary authors, including in particular Vittorini, Pavese, Hemingway, Faulkner, Steinbeck, Fitzgerald. After the war, Pomodoro obtained a diploma as a surveyor and enrolled in the Faculty of Economics and Commerce of the University of Bologna. He works at the Pesaro Civil Engineers, with a consultancy assignment for the reconstruction of public buildings; between 1949 and 1952 he attended the Pesaro Art Institute, specifying his strong interest in scenography. Meanwhile, he reads classical and modern theatrical texts (Aeschylus, Sartre, Brecht).

In 1953 he left Pesaro, called to work in Como for six months. Then he moved to Milan and in 1957 he definitively abandoned the Civil Engineering Department, taking advantage of favorable conditions for those who voluntarily resigned: with the liquidation and together with his brother Giò Pomodoro, they found a studio in Milan, where they worked together for about ten years. Arnaldo Pomodoro's works are present in large squares (Milan, Copenhagen, Brisbane), in front of Trinity College of the University of Dublin, at Mills College in California, in the Department of Water and Power in Los Angeles, in the Cortile della Pigna of the Vatican Museums and in the major public collections in the world.

In 1991, the "Disco Solare", a gift from the Prime Minister's Office to the Soviet Union, was placed in front of the Youth Palace in Moscow, and in 1992 a large-scale work "Papyrus" was installed in the gardens of the new Post Office and Telecommunications in Darmstadt in Germany. In 1995 he created a sculpture in memory of Federico Fellini on behalf of the Municipality of Rimini, in 1996 the work "Sfera con sfera" with a diameter of 3.30 meters (10.82ft) was placed in the square of the United Nations in New York and in 1998 he was commissioned to build the portal of the Duomo of Cefalù.

Its main exhibitions took place at the Rotonda della Besana in Milan in 1974, at the Musée d'Art Moderne de la Ville de Paris in 1976, at the Forte Belvedere in Florence in 1984, at the Palazzo dei Diamanti in Ferrara in 1987, at the Hakone Open-Air Museum in Japan in 1994, at the Rocca Malatestiana in Cesena and at the Museum of the City of Rimini in 1995, at the Marlborough Gallery in New York in 1996 and at San Leo in 1997. He has held traveling exhibitions in American museums (from the University Art Museum of Berkeley, California, in 1970-71 and by the Columbus Museum of Art in Columbus, Ohio, in 1983-85) and again in Europe, Australia and Japan.

He has taught in the art departments of American universities: Stanford University, University of California, Berkeley, Mills College. Since 1990 he has directed the TAM Center for the training of young people, established in collaboration with the Municipality of Pietrarubbia in Montefeltro. He received the following awards: in São Paulo in 1963, in Venice in 1964, one of the six international prizes of the Carnegie Institute in 1967, the Henry Moore Grand Prix in Japan in 1981, in 1990 he received the Praemium Imperiale 1990 from the Japan Art Association for sculpture (Leonard Bernstein for music, Federico Fellini for cinema and theater, James Stirling for architecture, Antoni Tapies for painting).

In 1992 the Trinity College of the University of Dublin awarded him an honorary degree in literature, and in the same year he received the UBU Prize for the scenography of Koltes' opera "In the solitude of the cotton fields". In 1993 he was awarded the title of Honorary Member of the Brera Academy in Milan. In 1994 he received the Prize of the Presidency of the Council of Ministers of Italy as part of the "Big Millennium" study days organized by the Pio Manzù Center. In 1996 he was appointed Knight of the Grand Cross of the Order "Merit of the Italian Republic".

Arnaldo Pomodoro also devoted himself to scenography, particularly on major theatrical occasions: for Rossini's "Semiramide" at the Rome Opera in 1982, on the "ruins" of Gibellina from 1983 to 1985 for "Orestea" by Isgrò da Eschilo and in 1986 for Marlowe's "Didone", for Gluck's "Alceste" at the Genoa Opera in 1987, for Stravinsky's "Oedipus rex" in Siena in 1988, in summer 1989 for the poet's "Passion of Cleopatra" Egyptian Shawqi, in 1990 for "I Paraventi" by Genet, in 1992 for "In the solitude of the cotton fields" by Koltes, in 1993 for "Most grandiose abodes" by O'Neill and for "Oreste" by Vittorio Alfieri, in 1994 -95 for "Stabat Mater", "The Passion according to John" and "Vespers of the Blessed Virgin" by Antonio Tarantino and for "Moonlight" by Pinter. In 1996 he designed scenes for Eugene O'Neil's "Drammi Marini" and Jean Anouilh's "Antigone". In 1998 he created the sets and costumes for Shakespeare's "Tempest".

Lives in Milan since 1954; his studio resides next to the Porta Ticinese darsena.