Zinc oxide (ZnO) nanoparticles (NPs) have emerged as a significant area of research due to their distinctive physicochemical and biological properties. In this study, an eco-friendly and cost-effective synthesis of ZnO NPs was achieved using Alpinia officinarum (A. officinarum) rhizome extract in conjunction with Zinc nitrate hexahydrate as a precursor. The structural and morphological properties of the synthesized ZnO NPs were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). FTIR analysis confirmed the presence of functional groups associated with the phytochemicals involved in the synthesis process. Crystalline structure and particle size were validated through XRD and TEM analyses. The antimicrobial potential of the ZnO NPs was evaluated against Pseudomonas aeruginosa ATCC 25619, methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300, and Candida albicans ATCC 10231. Additionally, antibiofilm assays were conducted against the same microbial strains. The ZnO NPs demonstrated significant antimicrobial and antibiofilm efficacy. These findings suggest that biosynthesized ZnO NPs possess promising potential for application in biomedical coatings, pharmaceuticals, and cosmetic formulations. © The Author(s) 2025.