Basella alba aqueous leaf extract was employed for the synthesis of ZnO and Ag/ZnO nanocomposites (NC), eliminating the use of hazardous chemicals. UV‐visible spectroscopic analysis, X‐ray diffraction studies, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and X‐ray fluorescence spectroscopic analysis were used to determine the optical properties, crystalline structure, phytoconstituents, surface morphology, and elemental composition of the fabricated nanomaterials. The synthesized NC were employed as antioxidant in order to determine their free radical‐quenching effect. In vitro antibacterial activity assays exhibited their enhanced potential on selective gram‐positive and gram‐negative bacterial pathogens. The Ag/ZnO NC display a rapid catalytic reduction rate for rhodamine B, methylene blue, and methyl orange with degradation rates of 88 %, 90 %, and 92 %, respectively. Thus, an environmentally benign, cost‐effective synthetic methodology is presented for the size‐controlled synthesis of nanomaterials which act as multifunctional platform to alleviate organic pollutants.