Abstract: High-entropy oxides (HEOs), with their multi-principal-element compositional diversity, have emerged as promising candidates in the realm of energy materials. This review encapsulates the progress in harnessing HEOs for energy conversion and storage applications, encompassing solar cells, electrocatalysis, photocatalysis, lithium-ion batteries, and solid oxide fuel cells. The critical role of theoretical calculations and simulations is underscored, highlighting their contribution to elucidating material stability, deciphering structure-activity relationships, and enabling performance optimization. These computational tools have been instrumental in multi-scale modeling, high-throughput screening, and integrating artificial intelligence for material design. Despite their promise, challenges such as fabrication complexity, cost, and theoretical computational hurdles impede the broad application of HEOs. To address these, this review delineates future research perspectives. These include the innovation of cost-effective synthesis strategies, employment of in situ characterization for micro-chemical insights, exploration of unique physical phenomena to refine performance, and enhancement of computational models for precise structure-performance predictions. This review calls for interdisciplinary synergy, fostering a collaborative approach between materials science, chemistry, physics, and related disciplines. Collectively, these efforts are poised to propel HEOs towards commercial viability in the new energy technologies, heralding innovative solutions to pressing energy and environmental challenges.