After he graduated, Jon found work making travel and theater posters and advertising illustrations.
He zoomed in on people, usually pretty, young city women, and reduced the background to simple design elements.
During World War II, Whitcomb was commissioned a Lieutenant, Junior Grade in the United States Navy.
After a variety of duties, he was assigned as a combat artist for the invasions of Tinian, Saipan, and Peleliu.
He continued to produce story illustrations and covers for magazines, including McCall's and Playboy.