A multifaceted talent, Willis once even acted with Katherine Hepburn, in Alice Adams. In the late 1930s and early 1940s, he worked for Warner Brothers as a production-design and publicity artist. At the studio, he developed a friendship with Joe De Mers, who joined him in creating pin-ups for the Esquire Gallery.

The year 1950 was a banner one for Willis. Not only did he begin to supply illustrations to the nation’s major magazines, he was also inundated with advertising commissions from companies like Max Factor, Sunkist, and Pepsi Cola. Willis painted program covers for the Shipsteads and Johnson ice Follies from 1952 to 1969 and once accepted a commission for a billboard for the Stardust Hotel and Casino Lounge in Las Vegas. He wrote four classic art-instruction books for the Waiter Foster Company which have remained in print for more than forty years.