Born in Pittston, PA in 1916. He moved to New York City in 1933. He studied at the National Academy of Design for several years. He was awarded a three-year Tiffany Fellowship from 1937-1939. He won first prize for landscape painting in the 1939 Tiffany Exhibition of Fine Art which was held annually prior to World War II. From 1939 to 1940, he was a member of the research staff at the Metropolitan Museum of Art in New York, concentrating on Persian Art and also lectured on art at the New York 1939 World's Fair.
From 1941 to 1946, he served in the US Army. In the service, he was given the task of designing sets and costumes for musicals that entertained the troops, and he was commissioned to do a set of murals on the history of his regiment, which had to be abandoned when the war broke out. While in Normandy, Wall took to drawing the adopted troop cat named Tiger Lil. A series of his watercolors of war scenes were exhibited in London and Paris in 1947.
Upon his return to the United States, he resumed his art studies in 1948 at the Art Student's League. From 1949 to 1956, he worked as a free lance illustrator. In the late 1950's and early 1960's, Leon Wall was represented and exhibited many times at the Betty Parsons Gallery, which was known for its early promotion of Abstract Expressionist artists. At the time, he was considered one of the prominent artists in the early Abstract Expressionist movement.
Bennett Schiff (prominent Arts writer for the New York Post) reviewed his first one man show at the Betty Parson's Section 11 gallery in New York City (11 E. 57th St.) where he exhibited his series on American History, his Abstract Expressionist take on prominent incidents, and wrote: "Wall is controlled by a sense of entirely balanced taste. He is free. His work moves rhythmically; it takes precipitous directions; plunges, pitches, and flows, but it stops at the right time and the effect is maintained. His color, which is thinly applied and imaginative in both tonality and combination, is entirely seductive and pleasurable, and he knows how to use black and give his work structure, sustenance and color. There is an airy grace in this work, but there is an identifying substance behind it. Wall is comparatively new on the scene. He is a welcome addition."