Disch was born in Des Moines, Iowa, on February 2, 1940. Because of a polio epidemic in 1946, his mother Helen home-schooled him for a year. As a result, he skipped from kindergarten to second grade. Disch's first formal education was at Catholic schools; which is evidenced in some of his works which contain scathing criticisms of the Catholic Church. The family moved in 1953 to St. Paul in Minnesota, rejoining both pairs of grandparents, where Disch attended both public and Catholic schools. In the Saint Paul public schools, Disch discovered his long-term loves of science fiction, drama, and poetry. He describes poetry as his stepping-stone to the literary world. A teacher at St. Paul Central, Jeannette Cochran, assigned 100 lines of poetry to be memorized; Disch wound up memorizing ten times as much. His early fascination continued to influence his work with poetic form and the direction of his criticism.
After graduating from high school in 1957, he worked a summer job as a trainee steel draftsman, just one of the many jobs on his path to becoming a writer. Saving enough to move to New York City at the age of 17, he found a Manhattan apartment and began to cast his energies in many directions. He worked as an extra at the Metropolitan Opera House in productions of Spartacus for the Bolshoi Ballet, Swan Lake for the Royal Ballet, and Don Giovanni, Tosca and others for the Met. He found work at a bookstore, then at a newspaper. At the age of 18, a penniless, friendless, gay teenager, he attempted suicide by gas oven, but survived. Later that year, he enlisted in the army. Disch's incompatibility with the armed forces quickly resulted in a nearly three-month commitment to a mental hospital.
After his discharge, Disch returned to New York and continued to pursue the arts in his own indirect way. He worked, again, in bookstores, and as a copywriter. Some of these jobs paid off later; working as a cloak room attendant in New York theater culture allowed him to both pursue his lifelong love of drama and led to work as a magazine theater critic. Eventually, he got another job with an insurance company and went to school. A brief flirtation with architecture led him to apply to Cooper Union, where he was told he got the highest score ever on their entrance exam, but dropped out after a few weeks. He then went to night school at New York University (NYU), where classes on novella writing and utopian fiction developed his tastes for some of the common forms and topics of science fiction. In May 1962, he decided to write a short story instead of studying for his midterm exams. He sold the story, "The Double Timer", for $112.50, to the magazine Fantastic. Having begun his literary career, he did not return to NYU but rather took another series of odd jobs such as bank teller, mortuary assistant, and copy editor – all of which served to fuel what he referred to as his night-time "writing habit". Over the next few years he wrote more science fiction stories, but also branched out into poetry; his first published poem, "Echo and Narcissus", appeared in the Minnesota Review's Summer 1964 issue.