<p>The development of electrocatalytic CO₂ reduction reaction (eCO₂RR) in upgrading CO₂ into valuable products affords a substantially untapped opportunity to simultaneously achieve a circular economy and tackle environmental problems. However, the current challenges of this process lie in the low efficiency of eCO₂RR, less explored product-upgrading systems, as well as the unmet while key electrocatalysts. Here, we develop a parallel-integrated eCO₂RR cascade catalysis system based on a kind of covalent organic framework (Bpy-COF-Co) electrocatalyst with mesoporous nanosphere morphology that enables efficient cascade conversion of CO₂ into carbonyl compounds with high yields. In the parallel eCO₂RR modules, the specially designed Bpy-COF-Co with the advantages of high porosity, mesoporous nanosphere morphology and active Co sites presents a remarkable CO generation rate with a superior FE_CO (∼100%) and thus-generated CO can be simultaneously utilized in a series of backend carbonylation reactions (<i>e.g.</i>, amino-carbonylation, carbonylative Suzuki coupling, alkoxy-carbonylation and phenoxy-carbonylation). Noteworthy, this system can achieve gram-scale generation of valuable products like pesticide diethyltoluamide (1.81 g, 94.7% yield).</p>