Gelatin hydrogels (e.g., methacrylated gelatin gel, abbreviated GelMA gel) have garnered significant attention in tissue engineering and therapeutic drug and cell delivery due to their complete degradability and intrinsic ability to support cell adhesion. However, their practical applications are often constrained by their poor mechanical performance, which stems from their single network structure. This limitation poses significant challenges in load-bearing scenarios and restricts their use in advanced biofabrication technologies, where robust mechanical properties are essential. Here a hydrogel is developed composed entirely of gelatin using a phototriggered transient-radical and persistent-radical coupling (PTPC) reaction to achieve an optimized microstructure. This hydrogel features a phase-separated structure with enhanced interfacial bonding, significantly improving mechanical performance compared to conventional GelMA gels. Notably, this approach preserves the inherent properties of gelatin, including biocompatibility, cell adhesion, and degradability, thereby extending its applicability in the biomedical field, particularly in advanced biofabrication methods such as 3D printing. This approach offers a superior solution to meet the complex demands of sophisticated biomanufacturing technologies, expanding the potential applications of gelatin hydrogels in the biomedical field.