Nanocomposites have gained prominence in pharmaceutical formulation and delivery applications due to their tunable biophysical properties, including particulate size, surface characteristics, and morphology. Metal oxide nanocomposites with small size, uniformly dispersed particulates, edge surface sites, and lattice symmetry are mostly advantageous for biomedical applications. Additionally, these metal oxide nanocomposites are engineered at the molecular level to downgrade their toxicities using eclectic synthesis routes based on necessary biomedical 112requirements. Metal oxides are classified into two broad categories: magnetic, which mostly includes iron oxides, and nonmagnetic. Iron oxide nanocomposites with superparamagnetic properties have demonstrated efficacy for enhanced magnetofection and targeted drug delivery. Amongst nonmagnetic nanocomposites, zinc, titanium, and copper oxide have garnered attention in drug formulation due to their low toxicity in mammalian systems. This chapter explores an overview idea of the significance of magnetic and nonmagnetic metal oxide nanocomposites, their cytotoxicity profiles, and recent advancements in targeted drug delivery applications in the treatment of cancer, diabetes, and renal ailments. A few potential applications of these nanocomposites in the development of next-generation pharmaceuticals for the treatment of rare and neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, Lafora, and progeria were also investigated. The chapter helps the reader to the information of different recently available magnetic and nonmagnetic nanocomposites, their cytotoxicity toward various cell lines, and their targeted drug delivery applications toward cancer, diabetes, and renal ailments and consists of a novel idea of using these metal oxide nanocomposites for the treatment of rare and neurodegenerative diseases such as Lafora, progeria, etc.