John Sillito worked as the Archivist, Curator of Special Collections, and Professor of Libraries at Weber State University, where he was named the Nye Honors Professor for 2001-2002. He co-authored A World We Thought We Knew: Readings in Utah History with John S. McCormick in 1995, as well as A History of Utah Radicalism: Startling, Socialistic, and Decidedly-Revolutionary, which earned the authors the Best Utah History Book Award in 2012. In the field of Mormon studies, Sillito edited several volumes of personal essays, including The Wilderness of Faith and Essays on Mormonism. Additional writings have appeared in Utah Historical Quarterly, Sunstone, and Dialogue: A Journal of Mormon Thought.
In 2014, the Conference of Inter-Mountain Archivists awarded Sillito the Life-Time Achievement Award recognizing his 33 years of service and leadership in the archival profession. He is currently an adjunct history professor at Weber State.