Metacognition refers to the individual’s ability to recognize their cognitive processes, develop strategies based on these processes, and organize strategies appropriately for the situation. According to Flavell's model, metacognition enables the monitoring, evaluation, and, when necessary, organization of learning and thinking processes. Metacognitive knowledge is classified as declarative, procedural, and conditional knowledge. These types of knowledge increase the individual's awareness of their thoughts and make learning processes more effective. Metacognitive beliefs express the value an individual attributes to their thoughts and can be positive or negative. Positive metacognitive beliefs include the belief that worry or rumination can produce beneficial results. In contrast, negative metacognitive beliefs carry the fear that these processes may cause harm if they cannot be controlled. In psychopathologies, it is observed that negative metacognitive beliefs are common and individuals develop dysfunctional thought patterns. Regarding psychopathologies, it has been observed that disorders in metacognitive functions negatively affect cognitive processes and play an important role in the development of mental disorders such as anxiety disorders, depression, obsessive-compulsive disorder, post-traumatic stress disorder, and eating disorders. Inadequate metacognitive control can cause a person to establish dysfunctional thought patterns and develop maladaptive coping skills. The negative consequences of these processes can lead to poor prognosis for mental disorders. This review examines the basic concepts of metacognition and its relationship to mental disorders, emphasizing the effects of metacognitive processes on emotional regulation and cognitive appraisal. The study of metacognition makes important contributions to understanding the cognitive basis of psychopathology.