Abstract: The rapid development of the information society has driven wearable electronic devices to play an increasingly important role in fields such as health monitoring, environmental perception, and human-computer interaction. As an energy conversion device based on the coupling principle of contact charging and electrostatic induction, the triboelectric nanogenerator (TENG) can directly convert the low-frequency mechanical energy widely present in the environment into electrical energy. The ability to directly power wearable devices has become a research hotspot in the wearable field. Traditional thin-film or solid material-based TENGs have shown potential in energy harvesting, but their inherent defects, such as rigid base, poor air permeability, and poor adaptability to human movement seriously restrict their application scope in the wearable field. Yarn-based TENG can achieve essential wearable properties such as breathability, moisture permeability, and thermal management through material selection and structural design, and is more adaptable to human movement. It has broad application prospects in fields such as energy harvesting, power supply for wearable electronic devices, and self-powered sensing. This article introduces the basic principle of yarn-based TENG, the preparation materials of yarn-based TENG, the structure and preparation methods of yarn-based TENG, and the application of yarn-based TENG in the wearable field. Finally, it presents prospects for the preparation of fiber/yarn-based TENG and summarizes the challenges faced.