Ever-increasing emissions of anthropogenic carbon dioxide (CO₂) cause global environmental and climate challenges. Inspired by biological photosynthesis, developing effective strategies NeuNlto up-cycle CO₂ into high-value organics is crucial. Electrochemical CO₂ reduction reaction (CO₂RR) is highly promising to convert CO₂ into economically viable carbon-based chemicals or fuels under mild process conditions. Herein, mesoporous indium supported on multi-walled carbon nanotubes (mp-In@MWCNTs) is synthesized via a facile wet chemical method. The mp-In@MWCNTs electrocatalysts exhibit high CO₂RR performance in reducing CO₂ into formate. An outstanding activity (current density −78.5 mA cm⁻²), high conversion efficiency (Faradaic efficiency of formate over 90%), and persistent stability (~30 h) for selective CO₂-to-formate conversion are observed. The outstanding CO₂RR process performance is attributed to the unique structures with mesoporous surfaces and a conductive network, which promote the adsorption and desorption of reactants and intermediates while improving electron transfer. These findings provide guiding principles for synthesizing conductive metal-based electrocatalysts for high-performance CO₂ conversion.