Psoriasis is a chronic inflammatory skin disorder characterized by keratinocyte hyperproliferation, oxidative stress, and immune dysregulation. In this study, we developed a multifunctional, double-network hydrogel, composed of chitosan and poly(acrylic acid), embedded with cerium oxide nanoparticles (CeNPs) and betamethasone. The hydrogel harnesses the redox-catalytic properties of CeNPs to scavenge reactive oxygen species (ROS) while ensuring sustained betamethasone release for antibacterial and anti-inflammatory effects. Its mechanical stability and high water retention make it suitable for long-term skin application. In vitro, the hydrogel enhanced keratinocyte viability under oxidative stress and showed significant antibacterial activity against Escherichia coli. In a psoriasis-induced mouse model, the hydrogel significantly reduced epidermal hyperplasia, suppressed keratinocyte proliferation, and lowered inflammatory cytokine levels. The combination of antioxidant, antibacterial, and anti-inflammatory properties suggests that this hydrogel offers a promising therapeutic strategy for psoriasis, addressing both oxidative stress and inflammation for effective treatment.