Shaw played football professionally for a short time, but he needed to support his family, and so he began to write radio scripts for programs like "Dick Tracy" and "The Gumps." Of this, Shaw said, "Even when I was writing the junk, I knew it was junk; but I did it the best way I could ... and I make no excuses for eating. Or feeding a family. Or fighting for the freedom to write all these short stories, all these plays, all these novels."
Shaw wrote his play Bury the Dead (1936) for a contest for new playwrights held by the New Theatre League. Shaw missed the deadline, but he impressed them anyway, and they gave his play two off-Broadway performances. During this time, Shaw also began publishing his short stories in The Paris Review and The New Yorker.
Shaw enlisted in the military during World War II, and he worked with a camera crew. His crew traveled to Normandy two weeks after D-Day, and Shaw helped photograph battles for the liberation of French cities and towns, and this gave him the idea for his novel The Young Lions (1948). After the war, Shaw was blacklisted for a time, because he was mistakenly accused of being a Communist. Shaw claimed the blacklist "only glancingly bruised" his career. Still, he moved to Paris in 1951, and would remain abroad for 25 years, writing many stories, novels, and plays.
Irwin Shaw said, "If you organize chaos, you organize as much as you can to show that it's chaos. It's the way I do it. To pretend it's not chaotic is a lie."