<p>Rare earth metal-doped zinc sulfide (ZnS) nanoparticles have emerged as a fascinating class of II-VI semiconductor nanomaterials, offering tunable optical, electronic, and structural properties. These doped nanostructures exhibit enhanced luminescence, stability, and catalytic activity, making them highly promising for applications in optoelectronics, bioimaging, sensors, and photocatalysis. This comprehensive review explores the structural characteristics of ZnS nanoparticles, various doping strategies with rare earth metals, and their significant impact on material properties. Additionally, we discuss state-of-the-art synthesis techniques, surface modifications, and functional applications that establish ZnS as a key player in modern nanotechnology. By analyzing recent advancements and existing challenges, this review provides valuable insights into the future scope of rare earth metal-doped ZnS nanoparticles, paving the way for their integration into next-generation nanodevices.</p>