INTRODUCTION: The therapeutic application of cannabidiol (CBD) is gaining interest due to the growing body of evidence supporting its use in the treatment of mental disorders. OBJECTIVES: To develop a systematic review to evaluate the scientific evidence supporting the use of CBD in the treatment of psychiatric disorders. METHODS: Only double-blind randomized clinical trials were used. The search for scientific evidence was carried out in the PubMed and BVS databases, with the descriptors “cannabidiol” and “mental disorders”. A total of 219 articles were found in PubMed and 79 in BVS, between the years 2020 to 2022, in the English language. Review articles, observational studies, manuscripts, repeated articles and articles that did not focus on the treatment of mental disorders using cannabidiol were excluded. Thus, 10 relevant studies remained for the present systematic review. RESULTS: Of the 10 articles selected, 90% presented positive results for the use of CBD in the treatment of various mental disorders. Among them, there was a higher prevalence of the use of the drug for the treatment of psychosis, anxiety and behavioral mechanisms, evidencing its usefulness and benefits. It was observed that in cases of psychosis, CBD significantly increased glutamate levels in the left hippocampus of patients, proving its effectiveness. In the research involving behavioral mechanisms, it was possible to verify that the use of CBD linearly decreased the levels of cortisol linked to stress in the patient's body, evidencing its therapeutic capacity. CONCLUSION: The use of CBD was useful in alleviating the symptoms of some mental disorders, such as psychosis, anxiety, schizophrenia, autism, behavioral problems and stress. In addition, the research still showed uncertain and sometimes even contradictory results, which reinforces the need for further investigations on the action of this drug in the treatment of mental disorders.