As the necessity of eco-friendly energy storage devices grows, lithium-ion batteries (LIBs) have emerged as a promising alternative. While metal oxides, due to their high theoretical capacity, have been investigated as anode materials for LIBs, shortcomings such as poor electrical conductivity and segregation of metal oxide are obstacles in actual practice. To solve these problems, this study synthesized cobalt oxide/porous carbon (Co/CPC) composites through a facile one-step thermal process under gaseous carbon dioxide (CO2) atmosphere. As-prepared composites showed cobalt oxide nanoparticles well-integrated with the CO2-derived porous carbon (CPC) and exhibited superior electrochemical performance via a synergistic effect of the cobalt oxide and the CPC. The composites demonstrated a reversible capacity of 1179 mA h.g(-1) at a current density of 1000 mA.g(-1) and stably retained this capacity over 300 cycles. Therefore, Co/CPC composites prepared from CO2 can be economical and eco-friendly anode materials due to their green synthesis route and outstanding electrochemical performance.