High-entropy alloys (HEAs) represent a novel class of materials that challenge traditional alloy design principles by incorporating five or more principal elements in near-equiatomic ratios. This unique composition results in enhanced mechanical properties, thermal stability, and corrosion resistance. Recent research highlights the significant potential of HEAs in catalysis, particularly in solar- and thermo-related applications. Their high configurational entropy not only stabilizes single-phase structures but also facilitates unique electronic and catalytic behaviors. The tunability of HEAs allows for the optimization of their physical and chemical properties, enabling improved reaction rates and selectivity in various catalytic processes. This review provides a thorough overview of HEAs, covering their evolution, synthesis methods, characterization techniques, and computational modeling approaches. We critically assess the fundamental properties and underlying mechanisms driving their exceptional catalytic performance, and explore their current and potential applications in catalysis. By identifying key challenges and promising directions, we aim to guide future research toward unlocking the full potential of HEAs in catalytic systems.