Potassium channels constitute the most diverse group of ion channels and play a key role in regulating neuronal excitability and cardiac electrical activity. Despite significant progress in understanding their structure and function, the relationship between specific genetic alterations and disease phenotypes remains insufficiently systematized, which underscores the relevance of a comprehensive analysis of available data. This review summarizes findings from studies of animal models carrying mutations in potassium channel genes, aimed at elucidating their physiological roles and the molecular mechanisms of pathogenesis. Knockout models of kcna1, kcna2, and kcnq2 reproduce key features of human epileptic syndromes, including neuronal hyperexcitability, spontaneous seizures, and early mortality. Deficiency of kcnma1 is associated with impaired motor coordination and the development of cerebellar ataxia. Mutations in kcnq1 and kcne1 result in cardiac and auditory abnormalities characteristic of Jervell and Lange-Nielsen syndrome, whereas double knockout of kcne1/kcnh2 leads to a pronounced susceptibility to ventricular arrhythmias. In addition, deletion of kcnd2 and kcnd3, encoding Kv4 family channel subunits, reveals their critical role in shaping the early phase of cardiac repolarization. Thus, the systematization of data on genetically modified animal models enables the establishment of links between molecular defects in potassium channels and clinical manifestations of disease, and highlights their importance as tools for the development and testing of novel therapeutic approaches.