Lysine itaconylation is a novel post - translational modification (PTM) that was recently discovered in macrophage proteomes mediated by the immunoregulatory metabolite, itaconate. However, there is currently an absence of comprehensive and high - accuracy analytical methods for the global identification of itaconylation sites in proteomes, which limits its biological function study. Here, we developed a thiol-based bioorthogonal probe, BMAyne, to site-specifically profile itaconylation in macrophage proteomes by a quantitative chemoproteomic strategy. Notably, 29 endogenous itaconylated proteins were identified in lipopolysaccharide (LPS)-stimulated macrophages using BMAyne, which complemented the results obtained by promiscuous antibody enrichment. Our effort provides a unique chemical tool to enrich endogenous lysine itaconylation and establishes a rich database for guiding subsequent functional studies of this unique PTM.