This chapter delves into the evolution, mechanisms, and clinical applications of implantable neurotechnology, tracing its origins from early electrical stimulation studies to modern advances like spinal cord stimulators, brain–computer interfaces, and responsive neurostimulation. Highlighting innovations in materials science, microelectronics, and neurophysiology, we discuss treatments for conditions such as epilepsy, chronic pain, and motor disorders. Each device’s functionality, from spinal cord stimulation’s role in chronic pain management to deep brain stimulation’s use in movement disorders, is examined alongside emerging techniques like closed-loop systems and targeted therapies. Ethical considerations, including cybersecurity and data privacy, underscore the importance of safeguarding these technologies. Opportunities for personalized treatments, interdisciplinary collaboration, and wireless advancements suggest a transformative future for neurotechnology, with potential for more precise, real-time therapeutic interventions. This chapter also addresses challenges in device biocompatibility and patient-specific treatment optimization, framing a path for further innovation in neurotechnology.