<p>By integrating energy storage with carbon dioxide (CO₂) utilization, metal–CO₂ batteries can contribute to net-zero energy storage and carbon management. However, challenges related to performance, cost and safety continue to hinder their commercial deployment. In this Review, we discuss two types of metal–CO₂ battery — aqueous and non-aqueous — and examine their fundamental mechanisms, key component features and potential applications. In both systems, bifunctional catalysts and gas-diffusion layers are critical for efficient cathode reactions. Electrolyte design in non-aqueous systems must enable robust formation of the solid electrolyte interphase and broaden the operating temperature range (–120 °C to 50 °C). Aqueous systems need to suppress hydrogen evolution and carbonate formation effectively to ensure efficient CO₂ reduction. Improving anode and separator stability, as well as optimizing cell configuration to ensure safe operation, are essential for long-term battery performance. Environmental and economic assessments reveal that most of the CO₂ emissions and costs stem from cell components, requiring cost-efficient fabrication methods and recycling strategies to achieve sustainable and scalability targets. Future research should focus on integrated design principles that combine advanced materials, cell engineering and sustainability evaluation to unlock the full potential of metal–CO₂ batteries as next-generation energy-storage and CO₂-utilization technologies.</p>