Some of de Camp's most famous works were the short novels Lest Darkness Fall (1939), The Wheels of If, (1940) and The Glory That Was (1960). He also wrote the "Harold Shea" series with Fletcher Pratt as well as the Tales from Gavagan's Bar. de Camp is often credited for a resurgence of interest in Robert E. Howard's Conan character, and he wrote several novels about Conan.
L. Sprague de Camp was the guest of honor at the 1966 World Science Fiction Convention and has won the Nebula Award as a Grandmaster (1978) and the Hugo Award in 1997 for his autobiography, Time and Chance. In 1976, he received the World Science Fiction Society's Gandalf Grand Master award. In 1995, he won the first Sidewise Award for Alternate History Lifetime Achievement Award.
During World War II, de Camp worked at the Philadelphia Naval Yard with fellow authors Isaac Asimov and Robert Heinlein.
De Camp died on November 6, 2000, only seven months after his wife of sixty years, Catherine Cook de Camp, died. He died on what would have been her birthday.