The mineralocorticoid receptor (MR) mediates aldosterone effects on salt homeostasis and blood pressure regulation. MR activation also promotes inflammation, cardiovascular remodelling and endothelial dysfunction, and affects adipose tissue differentiation and function. Some of these effects derive from MR activation by glucocorticoids. Recent epidemiological studies show that the incidence of metabolic syndrome increases across quartiles of aldosterone, implicating the MR as a central player in metabolic homeostasis, involving electrolyte, water and energy balance. This review summarizes the current understanding of MR-mediated effects in diverse tissues and the role of aldosterone as a cardiometabolic risk factor, and discusses the possible relationship between inappropriate MR activation (by both mineralocorticoids and glucocorticoids) and the development of metabolic syndrome.