<p>Tellurium, long considered a toxic element, now represents a unique platform for biomedical nanomaterials. Its fundamental paradox lies in its dual nature: depending on the form and dose, it exhibits both potent pro-oxidant activity against tumor cells and pathogens, and pronounced antioxidant properties. Tellurium nanoparticles (TeNPs) serve as a tool for managing this duality. This review systematizes modern methods of TeNPs synthesis, including laser ablation as a source of high-purity particles, and details the mechanisms of their biological action - from redox activity and modulation of calcium signaling to the targeted suppression of signaling pathways. Particular attention is paid to the application of TeNPs as antimicrobial and anticancer agents, and as modulators of central nervous system functions, where particle size determines the shift from neurotoxicity to neuroprotection. The analysis suggests the potential of TeNPs for creating new therapeutic platforms, although challenges related to their narrow therapeutic window and long-term safety remain.</p>