Beaumont was born Charles Leroy Nutt in Chicago, to Charles H. and Letty Nutt. His mother is known to have dressed him in girls' clothes, and once threatened to kill his dog to punish him. These early experiences inspired the celebrated short story "Miss Gentilbelle", but according to Beaumont, "Football, baseball and dimestore cookie thefts filled my early world." School did not hold his attention, and his last name exposed him to ridicule, so he found solace as a teenager in science fiction. He dropped out of high school in tenth grade to join the army. He also worked as a cartoonist, illustrator, disc jockey, usher and dishwasher before selling his first story to Amazing Stories in 1950.