Abstract: Electrochemical CO2 reduction can generate C1 intermediates such as formate and CO, but its C-C coupling kinetics are sluggish. Microorganisms possess efficient carbon-chain elongation capability, yet are limited by a narrow substrate concentration window, low metabolic flux, and sensitivity to high ionic strength and metal-ion toxicity. The scale mismatch between the two processes is therefore the key bottleneck in electro-biocoupled CO2 conversion systems. This article reviews recent advances from four aspects: mechanism, interface, reactor, and system. It summarizes material design strategies, including electronic-structure regulation and interfacial water-activity control; compares the mass-transfer and stability characteristics of H-type cells, flow cells, and membrane electrode assemblies; highlights the importance of coordinated regulation of electrode structure, interface, and electronic state under low-CO2 conditions; and outlines the carbon-flux distribution of formate, CO, and acetate in the Wood-Ljungdahl pathway and the Calvin cycle. Two engineering coupling modes are emphasized: electrolyte-circulation tandem systems, which enable condition partitioning and continuous substrate supply through biocompatible electrolytes, and solid-electrolyte tandem systems, which deliver high-purity products while avoiding metal-ion toxicity. Achieving electro-biocoupled systems with high current density, high selectivity, and high biocompatibility requires coordinated advances in material design, interfacial stability, reactor engineering, and process regulation, thereby promoting the continuous and industrial conversion of CO2 into high-value chemicals.