Elucidating biological and pathological functions of protein lysine acetyltransferases (KATs) greatly depends on the knowledge of the dynamic and spatial localization of their enzymatic targets in the cellular proteome. We report the design and application of chemical probes for facile labeling and detection of substrates of the three major human KAT enzymes. In this approach, we create engineered KATs in junction with synthetic Ac-CoA surrogates to effectively label KAT substrates even in the presence of competitive nascent cofactor acetyl-CoA. The functionalized and transferable acyl moiety of the Ac-CoA analogs further allowed the labeled substrates to be probed with alkynyl or azido-tagged fluorescent reporters by the copper-catalyzed azide-alkyne cycloaddition. The synthetic cofactors, in combination with either native or rationally engineered KAT enzymes, provide a versatile chemical biology strategy to label and profile cellular targets of KATs at the proteomic level.