IntroductionBipolar disorder (BD) is a serious mental illness with a chronic course and significant morbidity and mortality. BD has a lifetime prevalence rate of 1%–1.5% and is characterised by recurrent episodes of mania and depression, or a mixture of both phases. Although it has harmacological and psychotherapeutic treatment, cognitive behavioural therapy (CBT) has shown beneficial effects, but there is not enough clinical information in the current literature. MethodsThe main aim was to determine the efficacy of CBT alone or as an adjunct to pharmacological treatment for BD. A systematic review of 17 articles was carried out. The inclusion criteria were: quantitative or qualitative research aimed at examining the efficacy of CBT in BD patients with/without medication; publications in English language; and) being 18–65 years of age. The exclusion criteria were: review and meta-analysis articles; articles that included patients with other diagnoses in addition to BD and that did not separate the results based on such diagnoses; and studies with patients who did not meet the DSM or ICD criteria for BD. The PubMed, PsycINFO and Web of Science databases were searched up to 5 January 2020. The search strategy was: “Bipolar Disorder” AND “Cognitive Behavioral Therapy”. ResultsA total of 1531 patients both sexes were included. The weighted mean age was 40.703 years. The number of sessions ranged from 8 to 30, with a total duration of 45–120 min. All the studies show variable results in improving the level of depression and the severity of mania, improving functionality, reducing relapses and recurrences, and reducing anxiety levels and the severity of insomnia. ConclusionsThe use of CBT alone or adjunctive therapy in BD patients is considered to show promising results after treatment and during follow-up. Benefits include reduced levels of depression and mania, fewer relapses and recurrences, and higher levels of psychosocial functioning. More studies are needed.