The increasing accumulation of CO₂ in the atmosphere has been leading to serious environmental problems. Electrochemical reduction of CO₂ is a potential means of carbon recycling for energy storage and environmental sustainability. However, it is limited by the lack of highly active and selective electrocatalysts. Here we demonstrate the development of mesoporous tin oxide (SnO₂) for electrocatalytic CO₂ reduction, which facilitates the adsorption and electrochemical reduction of CO₂ inside mesopores. The highly-ordered and uniform pore sizes of the mesoporous SnO₂ electrocatalyst favor the enhancement of formation of carbon monoxide (CO) and formate during the electrochemical reduction. The combined faradaic efficiencies of CO and formate reach a peak value of ∼80% at a current density of 5 mA cm⁻² at −0.8 V vs. reversible hydrogen electrode. This work suggests attractive development of mesoporous electrocatalysts with a variety of pore size and structures for efficient energy conversion and electrochemical CO₂ reduction.