In this study, a thermal-assisted precipitation method was applied for the uniform deposition of plasmonic Ag/Ag2O nanoparticles on the surface of needle-like Bi2O3 to synthesis Ag/Ag2O@Bi2O3 nanocomposite. The synthesized nanocomposite was characterized by different techniques including UV vis spectrophotometry, X-ray diffraction (XRD), scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray mapping, and photoluminescence (PL). The visible-light-driven photocatalytic activities of Ag2O@Bi2O3 and Ag/Ag2O@Bi2O3 were evaluated on photo-degradation of Reactive Black 5 (RB 5) dye as model pollutant. The effect of process variables including the initial dye concentration, reaction time, and pH on the photo-degradation of RB 5 was studied by Central Composite Design (CCD) methodology. It was found that the photo-degradation rate of Ag/Ag2O@Bi2O3 was higher than that of the Ag2O@Bi2O3 and Bi2O3. The highly efficient photocatalytic activity of Ag/Ag2O@Bi2O3 nanocomposite is mainly ascribed to enhancing photogenerated electron-hole separation and the surface plasmon resonance (SPR) influence of silver-based nanoparticles.