In our study, zinc oxide (ZnO) nanoparticles (NPs) were prepared by precipitation (economically and in high quality) at a temperature range of 60°C to 80°C and at pH 8, and were then adorned with graphene (G) plates. To determine its antimicrobial potential, the ZnO/G complex was loaded with metronidazole. The morphology and diameter of the ZnO nanocomposite before and after the loading were validated by scanning electron microscopy. The average size of the ZnO NPs was found to be 20–40 nm, while X-ray diffraction examined how the physical features of these NPs varied from those of its individual components with an average size of 28.1 nm. The assessment of the ZnO/G complex’s antibacterial efficacy against Gram-positive and Gram-negative bacteria was the main aim of our work. The agar well diffusion technique was used in order to assess the antibacterial activity of the ZnO/G complex with and without metronidazole. Our study demonstrates that the ZnO/G complex possesses antibacterial activity and might increase the antibiotic action by inhibiting Gram-positive bacteria (more than Gram-negative ones). It is, therefore, concluded that the ZnO/G NPs could be of use in formulating nano-drug conjugates that could act as antimicrobial agents.