The electrochemical reduction of carbon dioxide (CO2RR) currently attracts considerable attention as a way to make fuels and value-added products from CO2 using renewable energy. Much effort has been devoted to developing efficient electrode materials for this reaction, while changing the composition of the electrolyte presents an alternative method to tune the properties of electrochemical systems. Additives of soluble organic promoters can act directly as catalysts, i.e. in combination with a noncatalytic electrode, or as cocatalysts to enhance the activity of the electrode. In this review we classify and describe the roles of various organic promoters, to reveal how they lower the onset potential and increase the current density of the CO2RR and also, in some cases, influence the selectivity of the reaction. In addition, we highlight the key considerations that are essential to prevent errors being made and are required to pave the way toward industrial implementation.