The electrocatalytic conversion of CO₂ to produce fuels and chemicals holds great promise, not only to provide an alternative to fossil feedstocks, but also to use renewable electricity to convert and recycle the greenhouse gas CO₂ to mitigate climate problems. However, the selectivity and reaction rates for the conversion of CO₂ into desirable carbon-based products, especially multicarbon products with high added value, are still insufficient for commercial applications, which is attributed to insufficiently favourable microenvironmental conditions in the vicinity of the catalyst. The construction of catalysts/electrodes with confined structures can effectively improve the reaction microenvironment in the vicinity of the electrodes and thus effectively direct the reaction towards the desired pathway. In this review, we firstly introduce the effects of the microenvironment at the electrode–electrolyte interface including local pH, local intermediate concentration, and local cation concentration on CO₂ reduction reaction (CO₂RR) as well as the mechanism of action, and then shed light on the microenvironmental modulation within the confined space, and finally and most importantly, introduce the design strategy of CO₂RR catalyst/electrode based on the confinement effect.