Various types of energy exist everywhere around us, and these energies can be harvested from multiple sources to power micro-/nanoelectronic system and even personal electronic products. In this work, we proposed a hybrid energy-harvesting system (HEHS) for potential in vivo applications. The HEHS consisted of a triboelectric nanogenerator and a glucose fuel cell for simultaneously harvesting biomechanical energy and biochemical energy in simulated body fluid. These two energy-harvesting units can work individually as a single power source or work simultaneously as an integrated system. This design strengthened the flexibility of harvesting multiple energies and enhanced corresponding electric output. Compared with any indi-vidual device, the integrated HEHS outputs a superimposed current and has a faster charging rate. Using the harvested energy, HEHS can power a calculator or a green light-emitting diode patt. Considering the widely existed biomechanical energy and glucose molecules in the body, the developed HEHS can be a promising candidate for building in vivo self-powered healthcare monitoring system.