Bacterial infections significantly impede wound healing and can lead to severe complications, posing a substantial threat to public health. In this study, we developed polydopamine-polyethyleneimine (PDA-PEI) nanoparticles with photothermal properties, loaded with the antimicrobial peptide Polymyxin B (PMB), to address bacterial infections and promote wound healing. The dendritic structure of PEI enhances drug loading capacity, while the photothermal effect of PDA, activated by near-infrared (NIR) light, synergistically enhances the antibacterial efficacy of PMB. The synthesized PDA-PEI-PEG-PMB (P4) nanoparticles demonstrated excellent biocompatibility. They achieved over 96% inhibition againstStaphylococcus aureus(S. aureus) and 99.73% inhibition againstEscherichia coli(E. coli). The nanoparticles (NPs) exhibited a high photothermal conversion efficiency of 44.9%, enabling effective bacterial eradication under NIR irradiation. Furthermore, P4 NPs promoted angiogenesis and fibroblast activity, accelerating wound healing in a murine model. This study presents a promising strategy for combining photothermal therapy with antimicrobial peptides, offering a novel approach to wound care with broad-spectrum antibacterial activity and enhanced healing properties.