Wearable biosensors hold the potential of revolutionizing personalized healthcare and telemedicine. Advances in chemical sensing, flexible materials, and scalable manufacturing techniques now allow wearables to detect key physiological indicators such as temperature, vital signs, body motion, and molecular biomarkers. With these systems operating on the skin, they enable continuous and noninvasive disease diagnosis and health monitoring. Such complex devices, however, require suitable power sources in order to realize their full capacity. Emerging wearable energy harvesters are attractive for addressing the challenges of a wearable power supply. These harvesters convert various types of ambient energy sources (e.g., biomechanical energy, biochemical energy, and solar energy) into electricity. In some circumstances, the harvested electrical signals can directly be used for active sensing of physiological parameters. On the other hand, single or hybrid wearable energy harvesters, when integrated with power management circuits and energy storage devices, could power additional biosensors as well as signal processing and data transmission electronics. Self-powered sensor systems operate continuously and sustainably without an external power supply are promising candidates in the next generation of wearable electronics and the Internet of Things. This Account highlights recent progress in self-powered wearable sensors toward personalized healthcare, covering biosensors, energy harvesters, energy storage, and power supply strategies. The Account begins with an introduction of our wearable biosensors toward an epidermal detection of physiological information. Advances in structural and material innovations enable wearable systems to measure both biophysical and biochemical indicators conformably, accurately, and continuously. We then discuss emerging technologies in wearable energy harvesting, classified according to their capability to scavenge energy from various sources. These include examples of using energy ...