This study investigates the synthesis of ZnO nanoparticles from Citrus reticulata (mandarin) peel extracts and their characterization through XRD, SEM, and EDX to determine their size and composition. The results show that the ZnO nanoparticles possess a hexagonal structure with varying diameters and contain elements such as Ca, Cu, P, K, O, and Zn. Field emission scanning electron microscopy revealed that the nanoparticles exhibit semi-spherical, spherical, and bacilliform shapes. Various concentrations of ZnO nanoparticles were tested on adult Aphis fabae, with mortality rates ranging from 11% to 100%. The 2 mg/L concentration proved to be the most effective, achieving 96.66% toxicity, followed by 1.2 mg/L with 80% mortality, and 0.4 mg/L with 34.07% on the 4th day after application. Furthermore, the study revealed that all three concentrations showed the highest insect mortality on the 7th day post-application. These findings suggest that ZnO nanoparticles from Citrus reticulata could be a promising tool for pest control, particularly in managing Aphis fabae populations.