Zinc oxide nanoparticles (ZnO NPs) were produced using a simple green method, zinc citrate, and an aqueous solution of ginger extract. The aim of the study is to synthesize zinc oxide nanoparticles in a simple green way, diagnose their properties, and measure their antioxidants against free radicals. These NPs were investigated using ultraviolet-visible reflectance spectroscopy (UV-VIS), photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (EDX), respectively. Results showed that the estimated bandgap is 3.51 eV and that the PL intensity has one peak in the ultraviolet region (450 nm) and another in the visible region (590 nm) of the spectrum depending on the geometric shape and size of the ZnO NPs. It was concluded from this study that zinc oxide nanoparticles are synthesized by green synthesis ginger extract, which is a safe and environmentally friendly method. And when these nanoparticles were diagnosed by XRD, EDX, and AFM, it was found that they are of high purity and have a particle size of approximately 23.69 nm. Moreover, the antioxidant activity of ZnO NPs was determined against DPPH, where the particles showed a free radical scavenging capacity of 63.1% at 360 μg/ml, which gives good evidence for the antioxidant activity of ZnO NPs.