The photocatalytic and antibacterial activity of nickel oxide and silver-doped carbon quantum dots (NiO/Ag-CQDs) composites was investigated against malachite green dye and pathogenic bacteria such as Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative). The nickel oxide and silver-doped carbon quantum dots were prepared through the sonochemical and hydrothermal methods, respectively. The Ag-CQDs were dispersed on the NiO nanoparticles through the reflux method. The synthesized nanomaterials were analyzed using various techniques such as XRD, FTIR, UV-Vis spectrum, PL, and SEM with EDAX. The prepared nanomaterial exhibited 30.12 nm and 1.9 nm particle size for the NiO NPs and Ag-CQDs, and the equally distributed silver-doped carbon quantum dots throughout the surface of the NiO NPs were revealed through the SEM representations. From UV-vis spectra, NiO/Ag-CQDs exhibited an efficient photocatalytic degradation efficiency of 92 % for the MG dye in an aqueous medium within 135 min. TheNiO/Ag-CQDs composite exhibited antibacterial activity with 20.5 mm and 19.8 mm of the zone of inhibition for the gram-positive and gram-negative pathogenic bacteria, respectively. The observed results revealed that the prepared nanocomposite could be a potential composite for multifunctional application.