One-dimensional semiconductor nanomaterials form the basis for new technologies as well as driving the evolution of existing ones. Although these various technologies are in different stages of development, from nucleation to pilot production, it is difficult to ignore the tremendous potential they carry, overall, for next-generation concepts. One of the several areas that have been revolutionized by one-dimensional nanostructures, and which could not have happened at a more critical time, is energy. This review outlines the impact that one-dimensional semiconductor materials are having on energy production and conversion technologies. Instead of being extensive, we provide key developments in the areas of light-emitting diodes, solar cells, photoelectrochemistry and fuel cells.