Born in 1901 in Pistoia, Marini was trained as a painter in the great Renaissance art center of Florence at the Academia di Belle Arti. He drew small subjects from life, such as flowers, birds and insects, and he also sculpted. Marini worked intensively, experimenting with different materials, from terracotta to wood and plaster combined with paint, which he also sometimes used with bronze in order to accentuate forms and express movement.

In 1928 he traveled to Paris where he made his début as a sculptor, studied with Picasso and other leading modern artists. He also was a close associate of Henry Moore. Marini later returned to Italy, settling in Milan and teaching in nearby Monza. During this period Marini exhibited at La Mostra del Novecento Toscano at the Galleria Milano in Milan.

Marini was strongly influenced by the suffering he witnessed in Italy during the war. In 1950, at about the time he was gaining worldwide prominence, he described his work, as part of a "new renaissance of sculpture in Italy, the new humanist, the new reality."

Marini's work has an elemental simplicity and has almost been limited, apart from his few portrait heads, to three themes: the female figure, the rider and horse and dancers and jugglers. All of these themes are symbolic, imbued with meaning and significance drawn from his own mythology. His typical female figure, the Pomona, Roman goddess of fruit trees and hence a symbol of fertility, is archetypal of the Mother Goddess. The rider and horse is a symbol equally universal and is often interpreted as man riding and controlling his instincts, the horse being the symbol of the animal component in man, often specifically, the erotic instincts. The third corner of Marini's personal mythical thematic triangle, the dancers and jugglers, are an extension of the overall optimism which breaks through in his sometimes cloudy vision. They display a vibrancy, an attempt to escape from the restraints and impositions of weight and space.

Marini gained international renown in the 1950s with three major exhibitions of his work in Amsterdam, Brussels, and New York where his "Great Horse" is displayed in the Rockefeller Collection. His best-known work is the large bronze horse and rider commissioned for the Guggenheim Museum in Venice, Italy. Marini's working life covered more than 60 years of prodigious and prolific activity. He has had exhibitions in almost every major city in the world and prizes, medals and awards were constantly accorded him. Though Marini died in 1980, his works - sculpture, painting and graphics - live on, a continuing testament to a "Master" artist.