As the growth of synthetic organic chemistry fields was tremendously enabled by various forms of catalytic principles, modern protein bioconjugation strategies also rely heavily on the power of catalysis for fundamental development and various applications. Catalytic transformations have revolutionized industries of small molecule synthesis over the century. Because there have been growing interests in chemically modified proteins as renewable resources and materials (e.g., batteries, supercapacitors, anti-bacterial materials, and enzymes ), catalytic chemical modification of proteins would hold great promise for industrial production of such useful bioconjugates to address the global challenges regarding energy and environments. In addition to the potential improvement of production efficacy of bioconjugates, catalytic platforms can also be leveraged for site-specific modification of proteins for production of therapeutically important agents such as antibodydrug conjugates. Furthermore, a range of chemical tools in biochemistry and chemical biology fields is predicated on catalytic systems enabling target-specific labeling in living systems. Those protein modification applications have been achieved by addressing challenges of protein-targeting catalysis such as aqueous environments, low reaction concentrations (often nM to μM), catalyst deactivation by protein functional groups, and mild reaction conditions (e.g., 37 °C or rt). Despite the substantial development of protein bioconjugation through catalysis, systematic analysis of catalytic bioconjugation has been simply lacking to date, even though numerous reports reviewed the advances of protein bioconjugation either in broader fashions including non-catalytic systems or with emphasis on specific catalysis types such as transition-metal catalysis. This review article is focused on impacts of design, selection, and applications of catalysts on protein bioconjugation purposes and categorized into seven types of catalytic transformation mechanisms. The scope of the review article is chemical modification of natural proteins comprised of 20 canonical amino acids, particularly methods without genetic engineering. Methods that can be applicable at a protein level are primarily discussed, and relevant work has been chosen based on arbitrary molecular weight cutoff of 5,000 Da. Importantly, the main focus is on catalytic strategies rather than residue-specific organization found in many existing protein modification review papers. Nonetheless, recognizing the practical importance of a list of catalytic bioconjugation methods organized by target amino acid residues and other factors, we included an excel file containing lists of the discussed literature as Supporting Information, in which readers can sort and analyze the collection of papers with a parameter of interest. Among the diverse catalytic systems, seven catalytic mechanisms were used for organization of the article (Figure ) as the catalysis types are serving as common organizing topics of major catalysis-focused journals such as Nature Catalysis, ACS Catalysis, and ChemCatChem. Although, strictly speaking, only catalytic amounts (i.e., less than the amounts of reactants) should be ideally used for a given catalysis system, bioconjugation processes that are mechanistically catalytic even with the necessary use of excess amounts of a catalyst have been included in this present review. Though bioconjugation often indicates bond formation for functionalization purposes, catalytic bond cleavage reactions were also discussed. Because the focal point of the article is nonenzymatic processes, we refer readers to enzymatic bioconjugation-specific reviews.