This work discusses new energy-harvesting circuits and designs for wearable electronics aimed at sustainable applications. The types of energy-harvesting technologies used in this study include photovoltaic, piezoelectric, and thermoelectric systems, and their efficiencies and performances are compared in real-life situations. After conducting experimental and computational investigations, the study concludes that the photovoltaic system is optimal for high-light-intensity environments, while piezoelectric and thermoelectric systems are ideal for mechanical vibrations and hot/cold spots, respectively. Real-life examples demonstrate how these circuits can be incorporated into wearable systems, reducing conventional battery power usage and increasing overall device autonomy. The study highlights the potential of these technologies to enhance the performance and energy efficiency of wearable electronics and identifies areas for improvement and further integration of energy-harvesting systems. The findings can be applied to enhance wearable device technology, particularly for discrete devices to operate autonomously without external support in various environments.