Sodium–glucose cotransporter (SGLT)2 inhibitors have been demonstrated to reduce cardiovascular events, particularly heart failure, in cardiovascular outcome trials. Here, we review the proposed mechanistic underpinnings of this benefit. Specifically, we focus on the role of SGLT2 inhibitors in optimising ventricular loading conditions through their effect on diuresis and natriuresis, in addition to reducing afterload and improving vascular structure and function. Further insights into the role of SGLT2 inhibition in myocardial metabolism and substrate utilisation are outlined. Finally, we discuss two emerging themes: how SGLT2 inhibitors may regulate Na + /H + exchange at the level of the heart and kidney and how they may modulate adipokine production. The mechanistic discussion is placed in the context of completed and ongoing trials of SGLT2 inhibitors in the prevention and treatment of heart failure in individuals with and without diabetes.