Nanostructured high-entropy materials (HEMs) and defect engineering have emerged as a revolutionary paradigm for energy storage and conversion due to their exceptional compositional flexibility and inherently stable single-phase. However, conventional nanostructures often suffer from sluggish reaction kinetics or severe structural degradation under the aggressive electrochemical environments. Integrating defect engineering into the severely distorted lattice of HEMs can solve this bottleneck by securely stabilizing high density of vacancies, dislocations, and stacking faults without inducing phase change. Thus, defect engineered ZnO1-x, TiO2-x, CoS1-x and ZrO2-x where oxygen and sulphur vacancies are in-situ engineered for the application of photochemical hydrogen generation, Li-ion batteries and supercapacitor applications. Moreover, rare-earth element based high-entropy nanostructure are becoming the forefront of current study in the area of charge-storage applications