After the war, Miller converted to Catholicism. He married Anna Louise Becker in 1945 and they had four children. He lived with science-fiction writer Judith Merril in 1953.

Between 1951 and 1957, Miller published over three dozen science fiction short stories, winning a Hugo Award in 1955 for the story “The Darfsteller”. He also wrote scripts for the television show Captain Video in 1953. Late in the 1950s, Miller assembled a novel from three closely related novellas he had published in The Magazine of Fantasy and Science Fiction in 1955, 1956 and 1957. The novel, entitled A Canticle for Leibowitz, was published in 1959.

After the success of A Canticle For Leibowitz, Miller ceased publishing. Although several compilations of Miller’s earlier stories were issued in the 1960s and 1970s. A radio adaptation of A Canticle for Leibowitz was produced by WHA Radio and NPR in 1981 and is available on CD. A radio adaptation of the first two parts was broadcast in the UK by the BBC in 1992. Further details can be found on the BBC Genome Project.

In Miller’s later years, he became a recluse, avoiding contact with nearly everyone, including family members; he never allowed his literary agent, Don Congdon, to meet him. According to science fiction writer Terry Bisson, Miller struggled with depression, but had managed to nearly complete a 600-page manuscript for the sequel to Canticle before taking his own life with a firearm in January 1996, shortly after his wife’s death.

The sequel, Saint Leibowitz and the Wild Horse Woman, was completed by Bisson at Miller’s request and published in 1997.