Preventing bacterial contamination, treating wound infections and promoting wound healing have been major challenges in wound care management. In this work, a novel wound dressing based on a zwitterionic polycarboxybetaine (PCB) hydrogel and antibacterial silver nanoparticles (AgNPs) was developed via a one-step method for the efficient treatment of infected wounds. The PCB-AgNP hydrogel exhibits effective antibacterial ability against both Gram positive bacteria (Saphylococcus aureus) and Gram negative bacteria (Escherichia coli). Furthermore, in a murine model, the PCB-AgNP hydrogel is found to efficiently treat S. aureus infection and accelerate cutaneous wound healing. After a two-week healing process, histological tests indicate that it can promote the reconstruction of intact epidermis, which is much faster than those treated with a commercial wound dressing (Duoderm® film). This new bifunctional wound dressing provides new opportunities for highly efficient skin wound care and management.