He was born and lived in Washington, D.C. In 1910, he was graduated from the law school of the National University and admitted to the District of Columbia Bar. He served in World War I; after his Army service he became editor of a group of trade papers in New York, where he taught medical jurisprudence and wrote technical articles and pulp magazine fiction.

His first published work was "The Law of the Movies", in The Motion Picture Magazine, December 1917. (His story "Painted Gold" may have been written earlier.) "Demons of the Night" was published in Detective Story Magazine in March 19, 1918, followed by "Was She Mad?" on March 25, 1918. He published "The Stone Image" in 1919. He introduced Jules de Grandin as a character in 1925, and continued writing stories about him until 1951.

In 1937 he returned to Washington to represent a chain of trade journals, and there subsequently became a government lawyer for the duration of World War II. He alternated between law and journalism all his life. He published over five hundred short stories.

His first book, Roads (a surprising new origin for Santa Claus, drawn from the original Christian legends), was published by Arkham House in 1948.

Ten of the Jules de Grandin stories were collected in The Phantom Fighter (Mycroft & Moran) (an imprint of Arkham House), 1966.

His writing was secondary to his career as a lawyer specializing in mortuary jurisprudence. He taught this subject at mortuary schools for many years, and for some 15 years was the editor of Casket & Sunnyside, a leading trade journal. His Jerome Burke stories are still published in the Dodge embalming magazine.

Quinn was a contemporary of Robert E. Howard, H. P. Lovecraft and Clark Ashton Smith.

A recent collection of stories by Quinn is Night Creatures, (2003) edited by Peter Ruber for Ash-Tree Press.