Abstract: High-entropy alloys (HEAs), designed based on the multi-principal element concept, break through the traditional alloy design strategy dominated by one or two principal elements. Owing to the superior comprehensive properties, including high strength, high hardness, excellent corrosion resistance, and remarkable thermal stability, HEAs have attracted the extensive attention in recent years. With the rapid development of powder metallurgy and additive manufacturing technologies, the powder-metallurgy-processed HEAs have emerged as a research hotspot in the field of advanced materials. Compared with the conventional casting methods, powder metallurgy can effectively improve the compositional homogeneity and microstructural refinement, enable the near-net-shape fabrication, and expand the capability for producing complex components. The fundamental theories and core effects of HEAs were systematically reviewed in this paper, with emphasis on the powder preparation techniques, such as mechanical alloying, gas atomization, electrode induction melting gas atomization, plasma rotating electrode process, and plasma spheroidization, as well as the consolidation and forming technologies, including spark plasma sintering, hot extrusion, hot isostatic pressing, and additive manufacturing. Furthermore, the strengthening mechanisms and performance advantages of powder-metallurgy HEAs in terms of mechanical properties, corrosion resistance, high-temperature stability, and irradiation resistance were summarized. The potential applications in nuclear energy, aerospace engineering, marine environments, and high-performance coatings were also discussed. Finally, the future challenges and development directions, including cost reduction, process optimization, and materials genome engineering design, were proposed.