Her 1956 book The Nun's Story was a best-selling novel which was made into an award-winning 1959 movie starring Audrey Hepburn and Peter Finch.

Another work, The Undiscovered Country: A Spiritual Adventure published by Little, Brown & Co. was a description of her years as a student of mystic G. I. Gurdjieff. She is also the author of Wild Place, a description of her experiences as the UNRRA Director of the Polish Displaced Persons (DP) camp at Wildflecken, Germany, after WWII. This work won the Atlantic Non-Fiction Award in 1952.

It was at Wildflecken that Hulme met a Belgian nurse and former nun named Marie Louise Habets, who became her lifelong companion. The Nun's Story is a slightly fictionalized biographical account of Habets' life as a nun.

No one questions that adults and children see the world differently. The former strive for understanding; the latter are captured by wonder...even in the aftermath of a natural disaster. In her 1938 fictionalized autobiography "We Lived as Children," San Francisco native Kathryn Hulme captured this difference, as her persona tells of watching San Francisco burn after the tragic 1906 earthquake.