Inspired by nature's sophisticated protein machinery—where self-assembly creates highly ordered nanostructures—researchers design artificial protein-based nanomaterials. Among these, protein-polymer conjugates integrate native protein activity with synthetic polymer versatility. We combined site-specific protein modification with advanced ATRP chemistry to develop an innovative self-assembly approach: site-specific in situ polymerization-induced self-assembly (SI-PISA). This method enables diverse protein self-assembly systems that preserve biological activity while significantly enhancing pharmaceutical properties, including pharmacokinetics, tumor targeting, and antitumor efficacy. In addition, we further developed a novel and efficient universal strategy leveraging a thermosresponsive deoxygenation agent, GOX-PDEGMA, for the synthesis and purification of protein–polymer conjugates under open-air conditions, and this strategy demonstrated excellent scalability, accommodating reaction volumes from 10 μL to 100 mL, and compatibility with monoclonal antibodies and cytokines, highlighting its potential for developing long-acting protein therapeutics, antibody-based drugs, novel vaccines, and in vitro diagnostic reagents. Building on these advances, we expanded its applications. This talk will also briefly introduce our recent works about using protein self-assemblies as remineralization template for enamel repair and multi-specific antibody platform for cancer therapy.