Joseph Iliu was born in Sibiu, Roumania. He is also known as Josef, Josif, Iosif and Ilyu. He studied at the fine arts schools of Cluj and Bucharest. Winner of the prestigious Prix de Rome, he lived there from 1942 to 1949 and then moved to Paris. From 1949 to 1951 he exhibited abstract and geometric paintings in solo exhibitions and at the Salon des Réalités Nouvelles. He was part of Groupe Espace, which brought together European artists, artisans and architects who advocated for a modern relationship between art and architecture.
Iliu arrived in Montréal in 1951 and joined the avant-garde art scene. He exhibited paintings at the Galerie Agnès Lefort in 1953 and was later part of a group show at the Montreal Museum of Fine Arts. He also joined the Non-Figurative Artists Association of Montreal. Illiu innovated in public art by proposing in 1955 to install geometric abstract pieces in front of modernist buildings. He enjoyed a prolific career as a muralist in the Montréal region and elsewhere: Québec, Canada, the United States. He created many wall pieces, primarily in mosaics and metal, and a few sculptures. His murals elicit great interest among art critics, as do his paintings. After 1968, he began spending time in France, and moved there in 1988.