During World War I he was a fighter pilot for the US Army. He stayed in Europe and worked as a war reporter. After the war, Gilpatric lived in Antibes and worked as a publicity agent. It was there where he got the inspiration for his Mr. Glencannon stories, which were published in the Saturday Evening Post. In 1940, he and his wife Louise returned to the USA. In 1943, his book "Action in the North Atlantic" was made in to a film. Louise was hospitalised in 1950. By accident, her medical status card was swapped with that of someone else and she was told she was terminally ill. The couple then decided to commit suicide together, which they did on 7 July of the same year. After their deaths, the medical error was noticed.
Other works include "Action in the North Atlantic", which was made into a movie starring Humphrey Bogart, and which was nominated for an Academy Award for best story in 1943. In "Flying Stories" Gilpatric describes the adventures of his early years as a pilot. His collection of short stories entitled "Brownstone Front" takes place in New York City during the end of the 19th century and the start of the 20th. His novel "French Summer," is a humorous romance which revolves around vacationers at the French Riviera in the late 1920's.
His character Francis X. Olvaney, illustrated as a crooked Tammany Hall politician responsible for dangerous slum areas, appears in stories contained in both "Brownstone Front" and "Flying Stories," lending credence to the opinion that many of Gilpatric's short stories are autobiographical in nature.
In 1938, Gilpatric published "The Complete Goggler," considered the first comprehensive guide to goggle fishing. This book is now considered a prized collector's item.