This study focusses on the preparation of silver sulphide (Ag₂S) and Cu-doped Ag₂S (Cu/Ag₂S) nanoparticles (NPs) by sol-gel method and demonstrated their photocatalytic and antibacterial applications. The X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analysis demonstrated that the prepared NPs are effectively crystallized in the polycrystalline single-phase monoclinic geometry of Ag₂S. The optical bandgap is significantly reduced, and for both the sample the average grain size is observed to have narrowed from 42 nm to 23 nm. Both NPs were confirmed to be spherical nature as observed by scanning electron microscopy (SEM), and the energy dispersive X-ray (EDX) spectroscopy analysis validated the presence of all necessary components at the expected concentrations in the obtained samples. Under the irradiation of sunshine, the photocatalytic properties of each sample were investigated for their ability to facilitate the photodegradation of a hazardous methylene blue (MB) dye in an aqueous solution. Cu/Ag₂S sample possesses a profound photocatalytic reaction for the destruction of MB dye. Furthermore, the Cu-doped Ag₂S NPs suppress the proliferation of Staphylococcus aureus and Escherichia coli. In comparison to pure Ag₂S NPs, Cu/Ag₂S showed enhanced antibacterial activity against both the bacteria. Current study suggests that the Cu doped Ag₂S NPs could be a promising material for wastewater treatment and antimicrobial agents.