Electroreduction of CO₂ to formic acid has attracted extensive attention, because it is a promising strategy to re-utilize CO₂ and reduce greenhouse gas emissions that may favor the mitigation of energy and environment issues. Although great efforts have been made to tune the structure and composition of catalysts aiming to improve CO₂ conversion efficiency, seldom studies have been focused on the support regulation. In this work, ordered, porous TiO₂ nanotube arrays have been used as model support to study the impact of pore structure for CO₂ electrochemical reduction. It has been revealed that Pd supported on TiO₂ nanotube arrays substrate exhibits enhanced performance towards CO₂ reduction, showing a higher formate Faradaic efficiency of 20% over than Pd supported on TiO₂ film substrate. This study will shed new light on the design and synthesis of efficient catalysts by tuning the morphology of support for CO₂ conversion.