The integration of energy harvesting and sensing is core to the enhancement of intelligence and sustainability of wireless body area networks (WBANs). Much of the harvested energy from human motion carries rich state information. How to decouple this state information while harvesting energy is the key to constructing next-generation WBANs. Herein, we present a battery-free WBAN based on an all-in-one power generating and sensing system (A-PGSS) towards state perception under all-weather conditions. The A-PGSS consists of a flexible triboelectric nanogenerator (F-TENG), a solar cell and a low-power circuit. The F-TENG serves both as an energy harvester and a sensor. The multiple A-PGSSs that make up WBAN distributed on the clothing surface can harvest energy from human motion and sunlight. The low-power circuit is divided into two routes, one to manage and store energy for powering its own system, and the other to decouple, process, and send the state information carried in the electrical signal. The real-time state information can be remotely transferred and displayed on smartphones and computers, exhibiting excellent potential in wilderness expeditions and elderly healthcare. This work not only provides diverse options for developing multi-functional sensor nodes but also advances the practical application of novel battery-free WBANs.