While at Yale University (1922–24), Arno was particularly interested in music and organized his own band. He also decorated screens and panels for restaurants. After leaving Yale he went to New York City, where he joined the bohemian life of Greenwich Village and continued to do decorative painting. He was about to give up art to join a band when one of his cartoons was accepted by the newly established New Yorker. His association with the magazine lasted until his death.

In the late 1920s Arno's cartoons for The New Yorker, dealing with the city's aristocracy, became well known, and by 1931 he was the author of four cartoon books. In 1931 he was co-author of Here Comes the Bride, a musical satire produced in October of that year. A good-looking, sophisticated man, Arno played an active part in the world he satirized. Lecherous clubmen and sabled dowagers appeared frequently in his cartoons, collections of which include Man in the Shower (1944) and Sizzling Platter (1949).