Current treatments for infections caused by multidrug‐resistant bacteria still remain challenging and therapeutic materials with high efficacy are of demand. Herein, a bactericidal nanocomposite was constructed by loading Roxarsone (ROX) onto nitrosylated mesoporous polydopamine (named mPDA@NO‐ROX). The designed nanocomposite exhibited considerable photothermal effect and controlled NO and ROX co‐delivery under the irradiation of near‐infrared laser (NIR) to achieve enhanced chemo‐photothermal antibacterial therapy. The in vitro antibacterial evaluation of the mPDA@NO‐ROX demonstrated the effective elimination of the Gram‐negative tetracycline‐resistant Escherichia coil and Gram‐positive methicillin‐resistant Staphylococcus aureus under mild NIR irradiation compared to merely ROX loaded unmodified mPDA, indicating the NO enhanced chemo‐photothermal therapy. In addition, the cytotoxicity experiments indicated that mPDA@NO‐ROX exhibited only 5 % of hemolysis rate and high cell viability at 1 mg mL−1 against mammalian fibroblasts, suggesting the excellent biocompatibility. In conclusion, the mPDA@NO‐ROX could be a promising candidate for anti‐infection therapy of multidrug‐resistant bacteria.