Abstract Nonafluorobutanesulfonyl azide is a shelf‐stable, cost‐effective and general diazo transfer reagent for the efficient synthesis of α‐diazo carbonyl compounds in excellent yields and in very short reaction times, under mild conditions. The diazo products can be readily isolated in pure form after a simple aqueous extractive work‐up that avoids chromatographic purification in most cases. Because of its high efficiency and wide substrate scope, shelf‐stability, relatively low cost, and ease of product purification, nonafluorobutanesulfonyl azide offers an advantageous alternative to other commonly used diazo transfer reagents.