The investigation of novel growth mechanisms for electrodes and the understanding of their in situ energy storage mechanisms remains major challenges in rechargeable lithium-ion batteries. Herein, a novel mechanism for the growth of high-purity diversified Li3VO4 nanostructures (including hollow nanospheres, uniform nanoflowers, dispersed hollow nanocubes, and ultrafine nanowires) has been developed via a microwave irradiation strategy. In situ synchrotron X-ray diffraction and in situ transmission electron microscope observations are applied to gain deep insight into the intermediate Li3+xVO4 and Li3+yVO4 phases during the lithiation/delithiation mechanism. The first-principle calculations show that lithium ions migrate into the nanosphere wall rapidly along the (100) plane. Furthermore, the Li3VO4 hollow nanospheres deliver an outstanding reversible capacity (299.6 mAh g−1 after 100 cycles) and excellent cycling stability (a capacity retention of 99.0% after 500 cycles) at 200 mA g−1. The unique nanostructure offers a high specific surface area and short diffusion path, leading to fast thermal/kinetic reaction behavior, and preventing undesirable volume expansion during long-term cycling.