To improve the light-absorption capability of wide-bandgap zinc sulphide nanoparticles (ZnS, 3.3 eV), we propose a strategy involving the incorporation of sharp-edged Ag{111} nanoprisms onto the ZnS surface (Ag:ZnS). The structural, morphological, and vibrational properties of Ag{111}:ZnS nanocomposites were investigated using state-of-the-art characterization techniques. The Ag{111} nanoprisms exhibit strong light absorption extending up to 600 nm, which is due to the localized surface plasmon resonance and the bandgap reduction of Ag{111}:ZnS compared to pristine ZnS nanoparticles. First-principles calculations further reveal that smaller Ag clusters form stronger interfacial binding with ZnS, promoting enhanced electronic coupling and facilitating charge transfer while suppressing carrier recombination. Consequently, the Ag{111}:ZnS nanocomposite achieves a photo-catalytic degradation efficiency of 73.29% toward Rh6G, with a corresponding rate constant of 0.0193 min(-1). Overall, this study demonstrates that Ag{111} nanoprisms substantially modulate the optoelectronic properties of ZnS and effectively promote the redox processes governing its photocatalytic activity.