A New York native and the son of two Holocaust survivors, he told NPR in a May 2008 interview that the stories his parents told him as a child "were the most grim and frightening that you can imagine" and gave him the impression "there was a darker circle around a very small bit of light," something that enabled him to relate to his own characters' sufferings.

Ardai's writing has appeared in mystery magazines such as Ellery Queen's Mystery Magazine and Alfred Hitchcock's Mystery Magazine, gaming magazines such as Computer Gaming World and Electronic Games, and anthologies such as Best Mysteries of the Year and The Year's Best Horror Stories. Ardai has also edited numerous short story collections such as The Return of the Black Widowers, Great Tales of Madness and the Macabre, and Futurecrime.His first novel, Little Girl Lost, was published in 2004 and was nominated for both the Edgar Allan Poe Award by the Mystery Writers of America and the Shamus Award by the Private Eye Writers of America;his second, Songs of Innocence, was called "an instant classic" by the Washington Post,selected as one of the best books of the year by Publishers Weekly,and won the Shamus Award. Both books were written under the alias Richard Aleas and have been optioned for the movies by Universal Pictures. Ardai previously received a Shamus nomination for the short story Nobody Wins and he received the Edgar Award in 2007 for the short story The Home Front.

Ardai's third novel, Fifty-to-One, was published in November 2008. It was the fiftieth book in the Hard Case Crime series and the first to be published under Ardai's real name.

His fourth novel, Hunt Through the Cradle of Fear, is part of a pulp adventure series he created in 2009, describing the globetrotting exploits of a modern-day explorer named Gabriel Hunt. Authorship of all the books in this series is credited to Gabriel Hunt himself.

In 2010, he began working as a writer and producer on the SyFy television series Haven, inspired by the Hard Case Crime novel The Colorado Kid by Stephen King. The first episode of Haven aired on July 9, 2010.

In addition to his writing and publishing activities, Ardai serves as a managing director of the D. E. Shaw group. Ardai attended Columbia University, where he graduated summa cum laude in 1991. He graduated from Hunter College High School in 1987.

Ardai is married to writer Naomi Novik. They live in Manhattan.