To develop a simple electrode manufacturing method and search for next-generation electrode material with excellent capacity and rate performance, here, we report a three-dimensional (3D) C-Si-SiC micro/nanoporous composite Li-ion battery (LIB) electrode synthesized in a single step from pure SiC powder using a continuous-wave fiber laser on a copper foil without using any binder or other conductive materials. Volcano and fishnet structures of 3D C–Si–SiC composite electrodes are designed and fabricated. After two initial activation cycles, the reversible charge capacities of the volcano and the fishnet structure electrodes are 206.9and 373.9 mAh g–1 at a 100 mA g–1 current density. The capacity of laser-processed SiC has been significantly improved compared to that of the pure SiC electrode, which shows only 15 mAh g–1 of reversible capacity. After 100 cycles, the volcano and fishnet structures remain at 40.6 (losing 80.4%) and 160.7 mAh g–1 (losing 57.0%). Compared to the volcano structure, the fishnet structure shows a higher capacity and better cycling performance. The associated mechanisms are discussed.