An energy-independent wearable electronic system is being researched, where the energy required for its operation is obtained from human body movements and heat flow. The system power source consists of an electromagnetic motion energy harvester (mass up to 70 g, peak power reaching 38 mW depending on the intensity of movement), a thermoelectric harvester (mass 112 g, peak power up to 3 mW), power converters and a storage capacitor. The functional part of the system consists of a temperature and humidity sensors and a wireless data transmission module, while the energy-aware power management and the main function control is accomplished by a microcontroller, maintaining a safe input voltage range by adjusting the average consumption of the device. Only off-the-shelf components that provide greater configurability and could utilize a broader harvested voltage range were used. This study demonstrates that using a common energy storage element provides an energy flow stabilization effect that reduces the overall power instability, which can be a limiting factor for a single energy harvester system. The prototype was tested in controlled environment by walking on a treadmill and provided the necessary amount of energy for a sustained system operation even during motion pauses. Electrical energy storage efficiency of the system averaged at 17 %, with a peak efficiency reaching 21 %.