Global warming is partly caused by massive emissions of carbon dioxide (CO₂), a greenhouse gas, in the atmosphere by industrial and other human activities. Consequently, there is a need for advanced methods to store and transform CO₂ into value-added chemicals, materials, and fuels. In particular, the electrochemical reduction of CO₂ into fuels and chemicals using renewable electricity appears as a long-term solution for the circular economy, yet this method is actually limited by low selectivity, activity, and stability of carbon–carbon coupling in aqueous electrolytes. Here we review the electrochemical reduction of CO₂ with emphasis on principles, electrocatalysts and production of compounds with either one carbon (C₁) or two or more carbons (C₂₊). We discuss the application of bimetallic, oxide-derived, and crystal facet compounds, and their defect engineering and structure tuning.