His paternal grandparents, who were Romanian Jews, had first emigrated to Winnipeg, Manitoba, before they moved to California in the United States.

After dropping out during his freshman year at Caltech, Turtledove attended UCLA, where he completed his undergraduate degree and received a PhD in Byzantine history in 1977.

His dissertation was The Immediate Successors of Justinian: A Study of the Persian Problem and of Continuity and Change in Internal Secular Affairs in the Later Roman Empire During the Reigns of Justin II and Tiberius II Constantine (AD 565–582).

He later explained that his editor at Belmont Tower did not think that people would believe the author's real name was "Turtledove" and came up with something more Nordic.

He has written several works in collaboration, including The Two Georges with Richard Dreyfuss, "Death in Vesunna" with his first wife, Betty Turtledove (pen name: Elaine O'Byrne); Household Gods with Judith Tarr; and others with Susan Shwartz, S. M. Stirling, and Kevin R. Sandes.

His Worldwar series received a Sidewise Award for Alternate History Honorable Mention in 1996.

[12] Within the genre, he is known for creating original alternate history scenarios, such as survival of the Byzantine Empire or an alien invasion during the middle of the Second World War.