Abstract: The rapid rise in atmospheric CO2 levels driven by fossil fuel combustion have worsened worldwide environmental crises, making efficient CO2 capture and conversion indispensable for achieving carbon neutrality. Photo/electrocatalytic CO2 reduction (peCO2RR) powered by renewable energy represents a promising strategy for converting CO2 into high-value chemicals and fuels. However, this process remains hindered by the intrinsic limitations of traditional catalysts. As emerging crystalline porous polymers, covalent organic frameworks (COFs) offers distinct merits toward peCO2RR, including tunable topological structures, atomically precise active-site design, large specific surface area and excellent chemical stability, which effectively address the inherent limitations of conventional catalytic materials. This review systematically summarizes recent advances in COF-based peCO2RR by exploring the intrinsic correlation between structural engineering and catalytic performance. We cover the precise design of 2D/3D crystalline pore structures, green synthetic strategies, and diverse functionalization routes. A comprehensive analysis of multi-mode catalytic mechanisms including photocatalysis, electrocatalysis, and their synergistic effects is provided. Furthermore, we focus on the oriented synthesis of C1 and C2 products, clarifying the core structural factors that tunes product selectivity. The critical roles of theoretical simulations and in-situ/operando characterization techniques in uncovering catalytic pathways and intermediate evolution are also highlighted. Lastly, we discuss the key challenges of COF-based systems in structural robustness, catalytic selectivity, scalable preparation and device integration, and put forward targeted prospects for rational design and practical applications. By moving beyond traditional laboratory metrics, this review aims to establish a comprehensive “structure-property-performance” roadmap, which offers fundamental design principles to bridge the gap between molecular-level engineering and industrial-scale applications, thereby accelerating the deployment of COF-based technologies in the drive toward global carbon neutrality.