Born in Baltimore, his family soon moved to New York City, where Will grew up and attended school.
After graduation, Oursler worked on the staffs of various Boston newspapers and began writing in earnest.
His first book, The Trial of Vincent Doon, was published in 1941, followed by Folio on Florence White in 1942.
After the war, he began contributing numerous articles and short stories to well known magazines such as Collier's and Reader's Digest.
He also co-wrote "My Life with Edgar Cayce by David E. Kahn, as told to Will Oursler", Doubleday ed., 1970.