Conrad Marca-Relli, nee Corrado Marcarelli, was born in Boston, Massachusetts on 5 June 1913 and his childhood was spent between the United States and Italy. His family moved to New York when he was thirteen years old and, in 1930, at the age of seventeen, he enrolled in Cooper Union where he studied for a year. He then worked for the Works Progress Administration (WPA) from 1935 to 1938. His first assignment was as a teacher at the Leonardo da Vinci Art School and later he worked in the easel and mural divisions. During this time he met fellow artists Willem de Kooning, Franz Kline, and John Graham and he won the Logan Medal of the Arts from the Art Institute of Chicago.

Marca-Relli served in the US Army between 1941 and 1945 and then returned to New York in 1946. In 1949, he joined other artists to form the "Downtown Group" whose workshop was located at 39 East 8^th Street in Greenwich Village. Artist members also included Willem de Kooning, Robert Motherwell, Franz Kline, Jackson Pollock, and Robert Rauschenberg and their focus was the exploration of the avant-garde. He was selected by his fellow artists to show in the Ninth Street Show held on May 21-June 10, 1951. It was organized by Leo Castelli and is considered the first exhibition of Abstract Expressionism.

In 1953 in Mexico he had run low on paint and began attaching strips of canvas to add texture to his painting, something which became a signature element of his work. Throughout the 1950s, Marca-Relli continued to work and socialize with the abstract expressionists and his work was shown alongside theirs at both the Stable and Kootz Galleries in New York. During this period, he taught a Yale University and, in 1953, he purchased a house near East Hampton at the Springs, next to Lee Krasner and Jackson Pollock who became close friends. During the ensuing years Marca-Relli experimented with materials and collage.

There were numerous solo exhibitions of Marca-Relli's work and the Whitney Museum mounted his first retrospective exhibition in 1967. His work is in the collections of the Carnegie Museum of Art, the Guggenheim Collection, the Metropolitan Museum of Art, and the Smithsonian American Art Museum.

In 1996 he and his wife, Anita Gibson, moved to Parma, Italy. Conrad Marca-Relli was named an honorary Italian citizen shortly before his death on 29 August 2000.