Born in Pittsburgh, Pennsylvania, Leavitt is a graduate of Yale University and a professor at the University of Florida. He has also taught at Princeton.

He is the author of Family Dancing, Equal Affections, The Page Turner, Martin Bauman, or A Sure Thing, The Lost Language of Cranes, While England Sleeps (for the publication of which he was sued by Stephen Spender), The Body of Jonah Boyd, and numerous short stories. His most recent novel is The Indian Clerk. Leavitt, who is openly gay, has frequently explored gay issues in his work.

At the University of Florida he is a member of the Creative Writing faculty and is also the editor of Subtropics magazine, The University of Florida's literary review. He divides his time between Florida and Tuscany (Italy), where he had many of his books translated.

In 1994—5, Leavitt was sued by poet Stephen Spender, who claimed Leavitt had plagiarized his memoir in While England Sleeps. Subsequently, Viking Press, Leavitt's publishers, agreed to delete a passage that closely paralleled Spender's. The publishers also agreed never to publish the manuscript that had become the subject of the charge of plagiarism. In addition, Spender claimed that not only had Leavitt plagiarized his writing, but that he had fictionalized his life, especially by adding graphic, even scatological, fantasies attributed to the character modeled after Spender (in particular, "allegedly using his relationship with 'Jimmy Younger'"). "If he wants to write about sexual fantasies, he should write about his own," the poet said. Passages in Leavitt's novel, before being "revised", closely paralleled passages in Spender's memoir, at times phrase by phrase.

Nonfiction

• Italian Pleasures (1996) (with Mark Mitchell)
• Pages Passed from Hand to Hand: The Hidden Tradition of Homosexual Literature in English from 1748 to 1914 (1997) (editor, with Mark Mitchell)
• In Maremma: Life and a House in Southern Tuscany (2001) (with Mark Mitchell)
• Florence, A Delicate Case (2003)
• The Man Who Knew Too Much: Alan Turing and the Invention of the Computer (2005)