DeCarlo was married, with a pregnant wife, and working as a laborer for his father when he began to pursue a professional art career. Circa 1947, answering an ad, he broke into the comic book industry at Timely Comics, the 1940s iteration of Marvel Comics. Under editor-in-chief Stan Lee, his first assignment was the teen-humor series "Jeanie". DeCarlo went uncredited, as was typical for most comic-book writers and artists of the era, and he recalled in 2001, "I went on with her maybe ten books. They used to call me 'The Jeanie Machine' because that was all Stan used to give me, was "Jeanie"... Then he took me off "Jeanie" and he gave me "Millie the Model". That was a big break for me. It wasn't doing too well and somehow when I got on it became quite successful."