Injectable hydrogels capable of undergoing an in situ sol–gel transition are of increasing interest in biomedical applications owing to their minimally invasive delivery, tunable mechanical behavior, and capacity for localized therapy. In this study, we report the development of a κ-carrageenan (κ-CG)/protonated chitosan (CS) hydrogel formed exclusively through physical crosslinking under mild, non-toxic conditions, thereby eliminating the need for chemical grafting or synthetic cross-linkers. Microscopic characterization revealed a uniform and interconnected porous network with smooth internal walls, favorable for nutrient transport and cell infiltration. Rheological analysis demonstrated a high storage modulus, confirming excellent elasticity and structural stability, while compression assays indicated strong mechanical resistance. The hydrogel further exhibited high injectability and strong adhesive properties, enabling precise placement in irregular or deep tissue defects. In vitro cytocompatibility assays using human dermal fibroblasts confirmed high cell viability and enhanced cellular proliferation and attachment, demonstrating a supportive bioactive environment. Importantly, in contrast to previously reported κ-CG/CS hydrogels, this system uniquely integrates injectability, mechanical robustness, and tissue adhesion into a single multifunctional platform for tissue repair. The injectable nature also supports site-specific application and the potential incorporation of therapeutic agents for controlled delivery. Collectively, these results establish the κ-CG/CS hydrogel as a distinct and versatile candidate for wound healing, tissue engineering, and broader regenerative medicine strategies [1,2].