<p>The rapid proliferation of Internet of Things (IoT) nodes and wearable devices presents a formidable challenge to the provision of sustained and reliable power for distributed, miniaturized, and implantable electronics. In response, the development of maintenance-free, self-powering technologies that harness ambient energy has emerged as a critical research frontier. Among the various ambient energy sources, low-grade thermal energy is particularly abundant and widely available. Thermoelectric generators (TEGs), which directly convert temperature gradients into electrical energy, offer a promising solution for continuously powering devices in the microwatt to milliwatt range. Bismuth telluride (Bi₂Te₃)-based TEGs have established themselves as a leading material system for constructing efficient and reliable self-powered units, owing to their exceptional thermoelectric performance near room temperature (300–500 K), well-developed fabrication processes, and established commercial viability. This review summarizes recent advances in Bi₂Te₃-based TEGs, focusing on material optimization, innovative structural designs, thermal management strategies, and system-level integration. It provides a detailed analysis of the implementation strategies and persistent challenges associated with key structural approaches, including thermal resistance matching, high-density integration, and flexible device architectures. Representative application scenarios are also reviewed, encompassing deployments in biological systems, industrial pipelines, and natural environments. Finally, the review outlines prospective research directions for Bi₂Te₃-based TEG self-powering technology, with the aim of accelerating its widespread adoption in IoT networks, wearable electronics, and distributed sensor systems.</p>