The development on mono-element nonmetallic materials is of great significance for achieving low-cost and highperformance conversion and storage of clean and renewable energy. As number of mono-element groups, boron has owned the intrinsic unique electronic deficiency and diversified crystal structures, and displayed the utilization potential in the energy conversion and storage fields. Especially, the various boron nanomaterials have attracted extensive attentions on the basis of their several properties, such as metallic and semiconductor characteristics, electrocatalytic activity, exceptional mechanical strength and thermal stability, which could meet the increasing demands for efficient energy conversion and storage materials. In this review, the recent advances of mono-element boron nanomaterials for energy conversion and storage have been summarized comprehensively. The experimental preparation methods, as well as physical and chemical and properties of boron nanomaterials are analyzed based on the classification of material morphologies. In addition, a special focus has been proposed on their plentiful applications as active/catalytic electrode materials in energy storage devices, and as electrocatalysts or photocatalysts in energy conversion systems. Finally, the challenges and potential opportunities have been discussed for mono-element boron nanomaterials in energy conversion and storage.