The aging global population has catalyzed a paradigm shift in healthcare, emphasizing disease prevention over treatment and underscoring the need for large-scale, long-term monitoring of physiological parameters. Wearable health monitoring devices have emerged as a pivotal solution, offering real-time physiological data collection across prevention, treatment, and rehabilitation phases, thus revolutionizing traditional health monitoring approaches. This paper explores the integration of advanced materials—conductive polymers, flexible carbon nanomaterial electrodes, and metal foil substrates—into wearable health technologies. These materials enhance device flexibility, biocompatibility, and non-intrusive monitoring capabilities, providing medical-grade data crucial for early diagnosis and treatment guidance. With the wearable device market projected to expand significantly, fueled by the Internet of Things (IoT) and device miniaturization, this study delves into the technological advancements in detection technologies for electrophysiological, physical, biochemical, and photoelectric signals. It also examines the challenges and future directions in wearable health devices, focusing on material innovation, device miniaturization, and the integration of plastic electronics to improve wearability, sustainability, and interactivity. Through systematic analysis, this paper aims to highlight the transformative impact of wearable health technologies on enhancing patient care, facilitating early disease detection, and offering personalized health management solutions.