To advance seaweed polysaccharide applications in hydrogel wound dressings, five antibacterial composite hydrogels (groups A~E) were synthesized using oxidized κ-carrageenan (OKC), acrylamide (AM), and progressively increasing concentrations of silver-based metal–organic frameworks (Ag-MOFs). Systematic characterization revealed concentration-dependent effects: (1) positive correlations were obtained for the moisture content (MC, maximized at 82.70% in E) and antibacterial efficacy (dose-dependent enhancement); (2) negative impacts were obtained for the swelling ratio (SR, E: 479% vs. A: 808%); and (3) high-dose drawbacks but low-dose benefits in terms of water resistance (WR), tensile strength (TS), elongation at break (EB), and microstructure were obtained. Group B demonstrated optimal Ag-MOFs loading, enhancing TS and EB, while excessive Ag-MOFs loading in C~E significantly degraded them (p < 0.05). Microstructural analysis showed severe 3D spatial damage in D~E. Furthermore, cytocompatibility assessments revealed that all groups maintained a cell viability exceeding 90%, demonstrating excellent biocompatibility. Among them, A~C showed a viability statistically equivalent to the control (p > 0.05) and were significantly higher than D~E (p < 0.05). In conclusion, group B emerged as the optimal Ag-MOFs formulation and exhibited superior WR, enhanced mechanical strength (TS and EB), and potent antibacterial activity while maintaining microstructural integrity and excellent biosafety. This Ag-MOFs/OKC/PAM hydrogel provides dual infection prevention and tissue support, maximizing seaweed polysaccharide benefits with excellent biocompatibility.