This study investigated the synthesis and characterization of ZnO NPs using different concentrations of orange fruit peel extraction. To reduce and stabilize, an aqueous medium containing extracts of orange peel was used. In the phytochemical study of orange peel extract, the results indicated the presence of phytochemicals such as flavonoids, alkaloids, tannins, glycosides, and phenolic compounds in the peel extract, which were confirmed by different screening tests. The decrease in conductivity observed during the synthesis process provided the initial evidence for the formation of ZnO NPs. The synthesized ZnO NPs were characterized using UV-Vis, FT-IR, XRD, SEM, EDX, and TGA techniques. The UV-Visible spectra of ZnO NPs prepared with varying concentrations of a reducing agent (0.5:2, 0.75:2, 1:2, and 2:2 ratios) were characterized to understand their optical properties. Each sample exhibited pronounced absorption peaks at wavelengths of 369.5, 372, 374, and 377 nm. These peaks correspond to band gap energies of 3.37, 3.34, 3.33, and 3.31 eV for the corresponding ZnO NPs samples. The optical band gap values decreased from 3.37 to 3.31 eV as the concentration of orange peel extract increased. FTIR spectroscopy was employed to characterize the functional groups present in the synthesized ZnO NPs. This analysis also revealed a Zn-O bonding absorption peak between 400 and 500 cm-1 . The structural properties were characterized by XRD. Based on the Debye-Scherer formula, ZnO NPs crystal size was determined to be 19.2 nm. TGA confirmed the presence of phytochemicals acting as capping agents, and the synthesized ZnO NPs exhibited thermal stability exceeding 670°C. The surface morphology of the ZnO NPs was characterized using a SEM. The spherical morphology of the ZnO NPs was confirmed by SEM imaging. The elemental composition of ZnO NPs was evaluated by EDX analysis of only zinc and oxygen, confirming the purity of the ZnO NPs sample.