Sculptor, painter, and printmaker Umberto Mastroianni’s formal training began as a teenager when he traveleld to Rome to study at the Accademia di San Marcello, and began apprenticing with his uncle Domenico Mastroianni in his sculpture studio. In 1926 he moved to Turin to work in the studio of classical sculptor Michele Guerrisi. In the year 1930 he was for the first time given an official award by the Ministry of Education, and then gradually were coming subsequent exhibitions on both - national and European level - in the year 1935 Quadrennial in Rome and the following year Biennale in Venice. Filippo De Pisis appreciated his creation a lot, mainly because he was inspired by the ancient art of sculpting, Egyptian and Hellenic sculptures. Drafted into Mussolini's military as World War II took hold, Mastroianni soon abandoned his service and joined the Resistance. At this time, he was exposed to the ideologies of Abstract Expressionism and was drawn to its sense of freedom, incorporating non-objectivity into his work throughout the 1940s.
In the mid 1940s he settled briefly in Paris, experimenting with entirely non-representational works. His first major show in this style was held at Paris' Galerie de France in 1952 to critical acclaim, and he soon established himself as a leading Italian abstractionist as well as a vocal proponent of European Modernism. He began exhibiting throughout Europe, the United States, and Japan, and he returned to Italy to take a position as headmaster at the Accademia delle Belle Arti, Bologna in 1960. That same year, he purchased a home in Marino, where he established a private studio while continuing to teach and exhibit. In the 1970s he began incorporating poetry into his daily routine, and wrote article as well on the topic of art for Rome's Il Messaggero. In 1990, he founded the Fondazione U. Mastroianni with works from 1935 - 1990. In 1993 his Monumento alla Resistenza was unveiled in Poggibonsi, Siena.  He continued to live and work in Marino until his death.