Nanostructured semiconductors have been researched intensively for energy conversion and storage applications in recent decades. Despite of tremendous findings and achievements, the performance of the devices resulted from the nanomaterials in terms of energy conversion efficiency and storage capacity needs further improvement to become economically viable for subsequent commercialization. Hydrogenation is a simple, efficient, and cost-effective way for tailoring the electronic and morphological properties of the nanostructured materials. This work reviews a series of hydrogenated nanostructured materials was produced by the hydrogenation of a wide range of nanomaterials. These materials with improved inherent conductivity and changed characteristic lattice structure possess much enhanced performance for energy conversion application, e.g., photoelectrocatalytic production of hydrogen, and energy storage applications, e.g., lithium-ion batteries and supercapacitors. The hydrogenation mechanisms as well as resultant properties responsible for the efficiency improvement are explored in details. This work provides guidance for researchers to use the hydrogenation technology to design functional materials.