Nanoparticle-based vaccines and immunotherapies take the lead in therapeutic innovations as they achieve higher efficiency and lower toxicity than their traditional counterparts. Nanoparticles as antigen/drug carriers are capable to be delivered to target cells and improve immune responses and selective therapeutic action. Such small molecules with large surface areas have the potential to controlled stability, bioavailability, and sustained, hence are adaptable for the treatment of infectious diseases, cancer, and autoimmune diseases. Such nanoparticles are capable of mimicking pathogens through presenting antigens, inducing an egalitarian humoral and cellular immune response. Targeted delivery with ligands, minimizing off-target toxicity. New generation nanoparticles have been engineered to deliver multiple antigens, adjuvants or therapeutic molecules simultaneously, potentially providing a fit for combinatorial therapies in complex diseases. Given their high clinical potential, however, regulatory difficulties, nanotoxicity, and scaling up manufacturing challenges, implementation remains insufficient. Researchers continue to study and conduct clinical trials to address these hindrances, bringing nanoparticle-based approaches closer to real-world applications. These innovations have the potential to revolutionize global health in the coming years, allowing to prevent and treat a wide range of diseases with more precision and effectiveness.