In 1955, he joined the École des Beaux-Arts (Fine Arts School) in Montpellier, where he met André-Pierre Arnal, Vincent Bioulès, Daniel Dezeuze, Toni Grand, François Rouan, and Henriette Pous, whom he married in 1962.
After doing his military service in Algeria from 1958 to 1961, he joined the École Nationale Supérieure des Beaux-Arts (the National Fine Arts School) of Paris, where he met fellow students Joël Kermarrec, Pierre Buraglio, and Michel Parmentier.
He discovered American art in Paris, notably the works of Kenneth Noland, Morris Louis, Sam Francis, and Mark Rothko.
In 1968, in Paris, Viallat had his first personal exhibition at the gallery led by Jean Fournier – who remained his gallerist for nearly thirty years.
Although he initiated this group and influenced it aesthetically through his pictorial works, he resigned on May 3, 1971, as he disagreed with the political and theoretical orientations imposed by Louis Cane and Marc Devade.