High-entropy oxides (HEOs) have gained significant attention in the field of rechargeable batteries due to their unique structural attributes, customizable compositions, entropy-driven stabilization effects, and superionic conductivity. This review aims to provide a comprehensive overview of HEOs, covering their fundamental concepts, structural characteristics, ionic conductivity, entropy stabilization effects, and various synthetic methods. HEOs exhibit superior physicochemical stability and tunable electrochemical properties, making them promising candidates for anode, cathode, electrolyte, and electrocatalyst materials in lithium-ion, sodium-ion, and lithium-sulfur batteries. The review highlights the advantages of HEOs, including enhanced structural stability, reduced reliance on rare elements, improved oxygen redox activity, and expanded material design space. HEOs can be synthesized using methods such as solid-state sintering, solvothermal synthesis, sol-gel synthesis, flame spray and nebulized spray pyrolysis, and electrospinning. Each method has its advantages and limitations, with solid-state sintering being the most conventional and straightforward, while solvothermal and sol-gel methods offer more control over morphology and composition. In the context of rechargeable batteries, HEOs have shown promising performance in anode and cathode materials. For anodes, HEOs exhibit excellent cycle stability and reversible Li-ion storage properties, particularly in rocksalt and spinel structures. For cathodes, HEOs enhance structural stability, reduce reliance on rare elements, improve oxygen redox activity, and expand the material design space. The review also discusses the role of different transition elements in HEOs, emphasizing their contributions to charge compensation, structural stability, and capacity enhancement. Overall, HEOs represent a promising direction for advancing the performance and sustainability of rechargeable batteries, offering a wide range of potential applications in energy storage and conversion technologies.High-entropy oxides (HEOs) have gained significant attention in the field of rechargeable batteries due to their unique structural attributes, customizable compositions, entropy-driven stabilization effects, and superionic conductivity. This review aims to provide a comprehensive overview of HEOs, covering their fundamental concepts, structural characteristics, ionic conductivity, entropy stabilization effects, and various synthetic methods. HEOs exhibit superior physicochemical stability and tunable electrochemical properties, making them promising candidates for anode, cathode, electrolyte, and electrocatalyst materials in lithium-ion, sodium-ion, and lithium-sulfur batteries. The review highlights the advantages of HEOs, including enhanced structural stability, reduced reliance on rare elements, improved oxygen redox activity, and expanded material design space. HEOs can be synthesized using methods such as solid-state sintering, solvothermal synthesis, sol-gel synthesis, flame spray and nebulized spray pyrolysis, and electrospinning. Each method has its advantages and limitations, with solid-state sintering being the most conventional and straightforward, while solvothermal and sol-gel methods offer more control over morphology and composition. In the context of rechargeable batteries, HEOs have shown promising performance in anode and cathode materials. For anodes, HEOs exhibit excellent cycle stability and reversible Li-ion storage properties, particularly in rocksalt and spinel structures. For cathodes, HEOs enhance structural stability, reduce reliance on rare elements, improve oxygen redox activity, and expand the material design space. The review also discusses the role of different transition elements in HEOs, emphasizing their contributions to charge compensation, structural stability, and capacity enhancement. Overall, HEOs represent a promising direction for advancing the performance and sustainability of rechargeable batteries, offering a wide range of potential applications in energy storage and conversion technologies.