Abstract Background The main focus of the non-pharmacological treatment of Gambling Disorder (GD) is the behaviour, cognition and motivation of the patient, addressing the psychological determinants of gambling. Although there is not a gold standard non-pharmacological treatment yet, many studies already had promising results, and the outcomes were even better when pharmacotherapies were combined with psychotherapies. This review intended to synthesise the efficacy of various available non-pharmacological therapies for GD evaluated in randomized controlled trials. Methods A systematic search was conducted in PubMed and in Cochrane Library for randomized controlled trials. Studies were included if participants had GD as their primary diagnosis and excluded if patients had other comorbidities. Results From 320 records identified, 22 studies were included in the critical appraisal. They included a total of 1694 patients, with a mean age of 42.94 years, and a 62.31% of males. Seven trials revealed the efficacy of cognitive behaviour therapy in improving significantly the outcomes. Three studies assessing cognitive therapy showed significant improvements in gambling symptoms, while one study showed improvements in gambling behaviour using exposure therapy. Combined or separate motivational interviewing and imaginal desensitization had significant results in 4 trials. Four other studies also showed efficacy for: couples therapy, node-link mapping therapy, 12-step facilitated and personalized feedback intervention. Physical exercise had promising results but did not reach significance. Conclusion The literature included in this review showed the heterogeneity of available psychotherapies. The majority of studies supported the efficacy of the tested therapies, while some of them, due to limitations such as small sample sizes or inadequate control groups, failed to reach significance.