One of the nanoparticles used in the medical world is ZnO nanoparticles. The purpose of this study was to synthesize ZnO nanoparticles by using peel's extract of kepok, ambon, and tanduk bananas (Musa paradisiaca L., Musa acuminata Cavendish Subgroup, and Musa x paradisiaca) as a capping agent. This research was conducted in four main steps, namely: extraction of three kind of bananas peel, phytochemical test on the bananas peel extract, synthesis of ZnO nanoparticles by using the extracts, characterization of ZnO nanoparticles by X-Ray Diffraction (XRD), and antibacterial activity test of ZnO nanoparticles. Based on the phytochemical test it was proven that bananas peel extract contained secondary metabolite such as flavonoids, polyphenols, alkaloids, and saponins in various concentration. The XRD analysis concluded that ZnO nanoparticles were successfully synthesized. Through the agar diffusion test, it can be showed that ZnO nanoparticles are a promising material as antibacterial agents. This statement is based on evidence that the diameter of the clear zone produced ranges from 8 to 10 nm.