Wearable sensor technologies provide continuous insight into the body’s physiological state and enable real-time feedback for timely intervention. Therefore, they play a critical role in the evaluation and improvement of the health and performance of individuals. Currently, commercialized wearable technologies are only capable of tracking physical activities and vital signs, and fail to unobtrusively access molecular-level information related to the body’s dynamic chemistry. To this end, sweat-based wearable biomonitoring is one of the most promising candidates to merge this gap. Sweat is a rich source of physiological information that can be retrieved non-invasively. It contains many critical analytes, which can be partitioned from blood with some degree of correlation. Therefore, in principle, sweat analysis can be used to provide non-invasive proxy measures of target biomarkers in blood for various clinical and physiological applications. Recent advances in electrochemical sensor development, flexible device fabrication and integration technology, and low power electronics have enabled the development of wearable sweat biosensors. However, despite such progress, the barrier to sweat-based health monitoring continues to be the inability to accurately infer physiologically relevant information from sweat measurements to enable actionable feedback. Here, we briefly review the significance of sweat-based monitoring and recent advances in sweat sensing technologies.