This chapter explores the transformative role of wearable technologies in advancing personalized and precision medicine. Precision medicine refers to the tailoring of medical treatment to the individual characteristics of each patient, including genetic, environmental, and lifestyle factors. The increase in health data through connected devices, such as smartwatches, biosensors, and implantable devices, provides continuous, real-time monitoring that supports data-driven, personalized, and individualized healthcare. The availability of big data relating to biological and disease features presents opportunities for more developed precision medicine approaches. Furthermore, the integration of artificial intelligence and machine learning with wearable devices enables precise disease prediction, therapeutic optimization, and model-informed precision dosing (MIPD), particularly in chronic and complex conditions like diabetes, neurodegenerative diseases, and cancer. Despite promising application, challenges such as data accuracy, interoperability, regulatory standards, and privacy concerns persist. Within the lens of precision and personalized medicine, this chapter reviews the structural and functional components of wearable devices, their integration with AI technologies, and their application in precision medicine, as well as the regulatory and ethical implications. This chapter concludes with future directions that emphasize AI integration, equitable access, and global standardization for enhanced health outcomes.