The electrocatalytic reduction of carbon dioxide (ECO2RR) is a promising method to transform waste into valuable materials, reducing carbon emissions, and producing clean energy and industrial products. This review introduces the complex mechanisms of ECO2RR based on the number of carbon atoms in the products, emphasizing the importance of C–C bond formation for high-value products. It systematically reviews the structural-activity relationships of electrocatalysts and provides a comprehensive classification of cutting-edge catalysts, including atomically-dispersed catalysts, alloys, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs). The review also discusses theoretical insights and challenges from both material and device perspectives to inspire further research and promote the industrial application of ECO2RR. Key challenges include the design of robust catalysts with high electrochemical activity and selectivity, the complexity of reaction mechanisms, and the need for efficient catalysts to overcome high activation energy barriers. The review highlights the role of electronic structure, vacancy defects, strain effects, and coordination environments in enhancing catalytic performance, providing a comprehensive overview of the current state and future directions in ECO2RR research.The electrocatalytic reduction of carbon dioxide (ECO2RR) is a promising method to transform waste into valuable materials, reducing carbon emissions, and producing clean energy and industrial products. This review introduces the complex mechanisms of ECO2RR based on the number of carbon atoms in the products, emphasizing the importance of C–C bond formation for high-value products. It systematically reviews the structural-activity relationships of electrocatalysts and provides a comprehensive classification of cutting-edge catalysts, including atomically-dispersed catalysts, alloys, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs). The review also discusses theoretical insights and challenges from both material and device perspectives to inspire further research and promote the industrial application of ECO2RR. Key challenges include the design of robust catalysts with high electrochemical activity and selectivity, the complexity of reaction mechanisms, and the need for efficient catalysts to overcome high activation energy barriers. The review highlights the role of electronic structure, vacancy defects, strain effects, and coordination environments in enhancing catalytic performance, providing a comprehensive overview of the current state and future directions in ECO2RR research.