We developed a novel, metal-free catalytic system for synthesizing a broad range of itaconates using α-ketoacids and allylic acetate. This method, leveraging phosphine and Mes-Acr+(BF4-) catalysts, has proven versatile, enabling the efficient itaconation of peptides, the synthesis of bioactive itaconates, and the preparation of an itaconate-based bio-orthogonal probe.