The uncontrolled discharge of industrial wastewater from textile industries has led to elevated concentrations of persistent contaminants, particularly textile dyes to the aquatic environment. Among these, Rhodamine B, a widely used carcinogenic dye, poses severe environmental and public health risks. This study addresses the pressing need for effective remediation techniques by developing zinc oxide nanoparticles (ZnO NPs) via a green synthesis approach using Azadirachta indica (neem) leaf extract as a chelating agent. Various characterization techniques, such as FTIR, XRD, FESEM, and UV–VIS spectroscopy, was applied to analyze the functional groups, morphology, and structural properties of the synthesized ZnO NPs. XRD analysis revealed that bioinspired ZnO NPs exhibited a hexagonal crystalline structure with diameters ranging from 12 to 30 nm, while those synthesized via the sol–gel method exhibited larger diameters (50–100 nm). FESEM analysis showed that bioinspired ZnO NPs displayed spheroid to flower-like shapes, whereas sol–gel-derived ZnO NPs were spheroid to rod-like in morphology. Under UV irradiation, the bioinspired ZnO nanoparticles demonstrated superior degradation performance, achieving 96.14% removal of Rhodamine B dye (30 ppm) with 2 g/L of nanoparticles at pH 7 within 120 min, whereas Sol–Gel-derived ZnO NPs achieved 93.46% degradation under similar conditions. These findings highlight the potential of bioinspired ZnO NPs as a sustainable and efficient solution for treating textile wastewater, paving the way for enhanced wastewater management in the textile industry.