An efficient protocol for the construction of 3‐carbonyl functionalized 4‐pyrones has been developed using a transition‐metal free thermal cascade reaction of diazodicarbonyls with β‐enamino esters or β‐enamino ketones. This reaction proceeds via cascade carbene generation, ketene formation via thermal Wolff‐rearrangement, nucleophilic addition, intramolecular cyclization, and elimination. This protocol provides a rapid synthetic route to diverse 2,3,5‐trisubstituted 4‐pyrone derivatives.magnified image