Electrocatalytic CO₂ reduction reaction (CO₂RR) is an attractive way to simultaneously convert CO₂ into value-added fuels and chemicals as well as to store intermittent electricity derived from renewable energy. However, this process involves multiple proton and electron transfer steps and is kinetically sluggish, thus leading to low conversion efficiency from electrical energy to chemical energy. Therefore, there is an urgent need to develop highly efficient CO₂RR catalysts with high activity, selectivity and stability. In this review, we firstly introduce the fundamentals of CO₂RR and then discuss the synthesis, characterization, catalytic performance and reaction mechanism of various catalysts based on specific CO₂RR products. The structure-performance relationships of some representative catalyst systems are highlighted, benefiting from advanced electrochemical in situ and operando spectroscopic characterizations. At the end, we illustrate existing challenges and emerging research directions, to design new generation of highly efficient catalysts and to advance both fundamental research and practical application of CO₂RR to low-carbon fuels and chemicals.