Nanoparticle-based drug delivery systems enhance therapeutic efficacy and precision by exploiting unique properties such as size, surface functionality, and encapsulation ability. This study reviews recent advances in nanoparticles including liposomes, polymeric nanoparticles, dendrimers, and metallic nanoparticles. Surface modification strategies like ligand attachment, PEGylation, and stimuli-responsive elements improve targeted delivery and controlled release. Applications in cancer, cardiovascular, and neurodegenerative diseases are highlighted, alongside integration with personalized medicine and gene therapy. Challenges in clinical translation, regulatory compliance, and manufacturing scalability are discussed, underscoring the transformative potential of nanoparticle-based therapeutics.