Abstract:High-entropy alloys (HEAs) are composed of five or more principal elements in equimolar or near-equimolar ratios, and exhibit distinctive properties including high-entropy effects, lattice distortion, sluggish diffusion, and cocktail effects. Platinum-group metal high-entropy alloys (PGM-HEAs) combine outstanding catalytic activity with superior corrosion resistance, and also exhibit notable functional properties in superconductivity and magnetocaloric refrigeration, which have rendered them a significant branch of HEA research. This review surveys the state of the art in PGM-HEAs, proceeding from compositional design through fabrication techniques to functional applications. In terms of compositional design, the review outlines multi-scale design methods based on phase-diagram calculations, first-principles calculations, and machine learning-assisted screening, with emphasis on the application of machine learning in adsorption energy prediction. For bulk PGM-HEAs, major fabrication techniques including vacuum melting, powder metallurgy, and laser additive manufacturing are summarized, followed by an assessment of research progress concerning mechanical properties, superconductivity, shape memory effect, and magnetocaloric performance. For nanostructured PGM-HEAs, both “top-down” and “bottom-up” synthesis strategies are categorized, and their application and mechanisms in electrocatalytic reactions, including fuel cells and water electrolysis for hydrogen production are discussed in detail. Finally, persistent challenges related to high material cost, scalable production, and compositional homogenization are analyzed, while future research directions including low-PGM alloy design, green synthesis methodologies, and multi-scale computational modeling are discussed.