In living cell membranes, K⁺ permeability is higher than that of other ions such as Na⁺ and Cl⁻ owing to abundantly expressed K⁺ channels. Polarized membrane potential is mainly established by K⁺ outward flow because the K⁺ concentration in the intracellular side is much higher than that in the extracellular side. We have found that the small synthetic molecule 1 is capable of self-assembling into selective K⁺ channels, enhancing K⁺ permeability and hyperpolarizing liposome membrane potential. Interestingly, molecule 1 also functions as K⁺ channel hyperpolarizing living cell membrane potential and relaxing agonist-induced blood vessel contraction. Therefore, it may have the potential to become a lead compound for the treatment of human diseases associated with K⁺ channel dysfunction.