Ault was born in Lenexa, Kansas and graduated from Baker University in 1907, before studying at Jesus College, Oxford as a Rhodes Scholar. While a student at Baker, he was a member of the local Zeta Chi fraternity. He then obtained a doctorate from Yale University in 1919, having served as a second lieutenant in the artillery in the First World War. He taught history at Boston University from 1913 to 1957, becoming William Edwards Huntington professor. He became an Honorary Fellow of Jesus College, Oxford in 1971. He was elected a Fellow of the American Academy of Arts and Sciences in 1941.
- "Warren O Ault". Social Security Death Index. New England Historic Genealogical Society. Retrieved 27 April 2011.
- Hub. Boston, MA: Boston University. 1927. p. 25.
- "Memoirs of Fellows and Corresponding Fellows of the Medieval Academy of America: Warren O. Ault". Speculum. Medieval Academy of America. 65 (3): 815–823. July 1990. JSTOR 2864141. doi:10.1017/s0038713400110693.
- "University News". The Times. 26 June 1971. p. 12.
- "Book of Members, 1780-2010: Chapter A" (PDF). American Academy of Arts and Sciences. Retrieved 27 April 2011.