This review systematizes the findings of contemporary research on decision-making in various forms of psychopathology. The analysis is based on a three-stage model of decision-making, which includes options generation, selecting the most advantageous option, and implementing the chosen decision. Functional impairment in patients' important life domains is considered from the perspective of dysregulation in the cognitive mechanisms of everyday decision-making at one or more of these stages. Thus, in some disorders, patients generate only a limited range of options (as in cognitive impairments or depression), while in others the number of options is excessive (as in attention deficit hyperactivity disorder or hypomania) or the options are peculiar (as in schizophrenia). At the stage of competitive option selection, some patients overestimate even minor risks (as in anxiety and depressive disorders), while others may be unreasonably confident in their predictions (as in mania, dementia, and psychoses). Finally, at the implementation stage, some patients may procrastinate, forget the decision, or revert to habitual behaviors (as in substance or gambling addictions), while others may initiate action prematurely (as in impulse control disorders). Such imbalances can occur occasionally in neurotypical individuals; however, in psychopathology they are persistent and inflexible. Further research into decision-making mechanisms will contribute to developing personalized methods of cognitive-behavioral therapy for mental disorders and relapse prevention.