De Lint's work is all (or nearly all) urban fantasy, or, to use his own term, mythic fiction. The chief theme is the existence of an ancient, mystical significance behind the world we see, which has only been obscured, not destroyed, by the passage of time. He studies the reactions of ordinary people to the living myth. Invariably, they are transformed by it.

In service of this, he places a high premium on characterization. Having established a character and his place in the world, De Lint pulls the rug out from under his world view, and invites us to watch him react. His magic is most often subtle and understated; the supernatural is a faint trace on the borders of the mundane world, and is rarely blatant. He draws from a wide variety of mythological sources, most frequently Native American and Irish. Some of his books also contain completely invented mythical elements. Many of these supernatural elements seem like archetypes to me, but you should ask a psychologist. Certain mythological types, notably the Wild Girl, Hunter, and Trickster, recur often throughout his books.