Born in Moundsville, West Virginia, Grubb wanted to combine his creative skills as a painter with writing, and attended the Carnegie Institute of Technology in Pittsburgh, Pennsylvania.
In 1940, Grubb moved to New York City where he worked at NBC radio as a writer while using his free time to write short stories.
Influenced by accounts of economic hardship by depression-era Americans that his mother had seen firsthand as a social worker, Grubb wrote The Night of the Hunter, which became an instant bestseller and was voted a finalist for the 1955 National Book Award.
That same year, the book was made into a film starring Robert Mitchum as the story's villain, sham preacher and fanatical serial killer Reverend Harry Powell.
Some of Grubb's short stories were adapted for television by Alfred Hitchcock and by Rod Serling for his Night Gallery series.