Zinc oxide nanoparticles (ZnO NPs) have gained significant attention in biomedical applications due to their excellent biocompatibility, low toxicity, and economic cost. These nanoparticles have shown promising potential in anticancer, antibacterial, antidiabetic, and anti-inflammatory activities, as well as in drug delivery and bioimaging. The synthesis methods of ZnO NPs include chemical precipitation, sol-gel, solid-state pyrolysis, solution-free mechanochemical, and biological methods. ZnO NPs induce cancer cell apoptosis through the generation of reactive oxygen species (ROS) and the release of zinc ions, which also contribute to their antibacterial activity by disrupting bacterial cell membranes. Additionally, ZnO NPs enhance the bioavailability of therapeutic drugs and have been shown to reduce blood glucose levels and improve insulin levels in diabetic rats. The luminescent properties of ZnO NPs make them suitable for bioimaging applications. Despite their promising biomedical applications, further research is needed to address issues such as toxicity, comparative analysis with other metal nanoparticles, and the development of evidence-based randomized studies.Zinc oxide nanoparticles (ZnO NPs) have gained significant attention in biomedical applications due to their excellent biocompatibility, low toxicity, and economic cost. These nanoparticles have shown promising potential in anticancer, antibacterial, antidiabetic, and anti-inflammatory activities, as well as in drug delivery and bioimaging. The synthesis methods of ZnO NPs include chemical precipitation, sol-gel, solid-state pyrolysis, solution-free mechanochemical, and biological methods. ZnO NPs induce cancer cell apoptosis through the generation of reactive oxygen species (ROS) and the release of zinc ions, which also contribute to their antibacterial activity by disrupting bacterial cell membranes. Additionally, ZnO NPs enhance the bioavailability of therapeutic drugs and have been shown to reduce blood glucose levels and improve insulin levels in diabetic rats. The luminescent properties of ZnO NPs make them suitable for bioimaging applications. Despite their promising biomedical applications, further research is needed to address issues such as toxicity, comparative analysis with other metal nanoparticles, and the development of evidence-based randomized studies.