Potassium (K⁺) channels are important in cardiovascular disease both as drug targets and as a cause of underlying pathology. Voltage‐dependent K⁺ (K_V) channels are inhibited by the class III antiarrhythmic agents. Certain vasodilators work by opening K⁺ channels in vascular smooth muscle cells (VSMCs), and K⁺ channel activation may also be a route to improving endothelial function. The two‐pore domain K⁺ (K_2P) channels form a group of 15 known channels with an expanding list of functions in the cardiovascular system. One of these K_2P channels, TREK‐1, is the focus of this review. TREK‐1 channel activity is tightly regulated by intracellular and extracellular pH, membrane stretch, polyunsaturated fatty acids (PUFAs), temperature, and receptor‐coupled second messenger systems. TREK‐1 channels are also activated by volatile anesthetics and some neuroprotectant agents, and they are inhibited by selective serotonin reuptake inhibitors (SSRIs) as well as amide local anesthetics. Some of the clinical cardiovascular effects and side effects of these drugs may be through their actions on TREK‐1 channels. It has recently been suggested that TREK‐1 channels have a role in mechano‐electrical coupling in the heart. They also seem important in the vascular responses to PUFAs, and this may underlie some of the beneficial cardiovascular effects of the essential dietary fatty acids. Development of selective TREK‐1 openers and inhibitors may provide promising routes for intervention in cardiovascular diseases.