Nanoscale materials have unique properties that make them especially useful for biomedical diagnostic applications. Recent developments in nanoengineering have resulted in increasing use of nanostructures in biosensors. Various types of 0D, 1D, 2D, and 3D nanostructures have been used to improve biosensor sensitivity, selectivity, limit of detection, and time to result, among other metrics. These nanostructures have been integrated into electrochemical, optical, and other biosensors for this purpose. Here, the most recent advances in the use of nanostructured materials in biosensors are described. This includes a discussion of nanoparticles, nanorods, nanofibers, nanopillars, nanowires, nanosheets, indented nanopatterns (nanoholes and nanoslits), nanogaps, nanochannels, nanopores, nanofunctionalized surfaces, and complex hierarchical structures and their unique advantages and applications in biosensors. Clinical applications of these nanobiosensors are also highlighted along with a discussion of the future directions for these materials in diagnostics.