In the realm of nanotechnology, the dawn of nanosensor era reveals the prominence of smallest of entities wielding prodigious impact. This chapter embarks on a journey to unveil the potential of electrochemical nanosensors in revolutionizing both diagnostics and therapy, promising to reshape the landscape of healthcare with unprecedented precision and efficacy. These miniature marvels hold the promise of unparalleled sensitivity, selectivity, and scalability when fabricated by nanostructured materials. This chapter provides an in-depth exploration of integration of varied nanomaterials in the fabrication of nanosensors. Functional materials at the nanoscale exhibit distinctive characteristics, including a significant surface-to-volume ratio, rendering them indispensable for biomedical diagnostics. Carbon-based nanomaterials like carbon nanotubes, carbon nanofibers, graphene and its derivatives, fullerene, and also diverse nanoparticles play a pivotal role in crafting the nanosensors, thereby augmenting the electrochemical readouts with substantially lower detection limit spanning multiple orders of magnitude. This chapter delves into the prominence of electrochemical nanosensors that hold the potential to revolutionize disease detection and treatment, paving the way for a new epoch of personalized and efficient therapeutic approaches.