Light-emitting materials in wearable biosensors have transformed health monitoring technology in many aspects. Since the discovery of light-emitting diodes (organic and inorganic), they have been utilized in various medical applications, enabling more accurate and long-term monitoring of essential vital signs. As material fabrication progressed, more promising light-emitting materials were integrated into wearable biosensors, developing significant possibilities for targeting potential diseases. Photoplethysmography (PPG) is a technique employed widely in wearable bioelectronics, operating light with different wavelengths (such as green, red, and infrared) to measure physiological parameters, such as heartbeat and blood pressure, for bio and medical applications. The health benefits of light-emitting medical-based technologies extended to the early prediction of crucial diseases relying on accurate long-term records leading to precise diagnosis of those diseases. The capability to continually track essential signs and diagnose diseases in their early stages leads to a more comprehensive recording of each patient's health profile, opening up possibilities for personalized medicine. This chapter discusses how light-emitting materials in wearable bioelectronics convey precise real-time health monitoring and continuous health tracking, improving patients’ treatment and leading to customizing medicine, where long-term monitoring data tailors therapies.