Exploiting the innate modularity of proteins has allowed advances across the fields of synthetic biology and biotechnology. By using standardized protein components as building blocks, complex, multiprotein assemblies with sophisticated functions can be generated; feats previously not possible with strictly genetic‐engineering approaches. The development of strategies for protein assembly is accelerating, pushing the boundaries of protein architecture. SpyTag and SpyCatcher protein ligase is a recent advance in this field that allows plug‐and‐play modularity by harnessing post‐translational protein assembly. Herein, we review the latest applications of this powerful tool including novel enzyme assemblies, modularizing protein display, and the generation of antibody and antibody‐like “devices” by using SpyTag/SpyCatcher technology.