AbstractAchieving scalable synthesis of nanoscale transition‐metal carbides (TMCs), regarded as substitutes for platinum‐group noble metals, remains an ongoing challenge. Herein, a 100‐g scale synthesis of single‐phased cobalt carbide (Co2C) through carburization of Co‐based Prussian Blue Analog (Co‐PBA) is reported in CO2/H2atmosphere under mild conditions (230 °C, ambient pressure). Textural property investigations indicate a successful preparation of orthorhombic‐phased Co2C nanomaterials with Pt‐group–like electronic properties. As a demonstration, Co2C achieves landmark photo‐assisted thermal catalytic CO2conversion rates with photo‐switched product selectivity, which far exceeds the representative Pt‐group‐metal–based catalysts. This impressive result is attributed to the excellent activation of reactants, colorific light absorption, and photo‐to‐thermal conversion capacities. In addition to CO2hydrogenation, the versatile Co2C materials show huge prospects in antibacterial therapy, interfacial water evaporation, electrochemical hydrogen evolution reaction, and battery technologies. This study paves the way toward unlocking the potential of multi‐functional Co2C nanomaterials.