We investigated whether adding hypnosis to CBT (CBTH) improved treatment outcomes for MDD with a two-armed, parallel-treated, randomized-controlled trial using anonymous self-report and clinician-blinded assessments. Expectancy, credibility, and attitude to hypnosis were also examined. Participants ( n = 66) were randomly allocated to 10-weekly sessions of group-based CBT or CBTH. LMM analyses of ITT and Completer data at post-treatment, six-month and 12-month follow-up showed that both treatments were probably efficacious but we did not find significant differences between them. Analyses of remission and response to treatment data revealed that the CBTH Completer group significantly outperformed CBT at 12-month follow-up ( p = .011). CBTH also displayed significantly higher associations between credibility, expectancy and mood outcomes up to 12-month follow-up (all p < .05 or better), while attitude to hypnosis showed one significant association ( r = -0.57, p < .05). These results suggest that hypnosis shows promise as an adjunct in the treatment of MDD but a larger sample size is required to fully test its merits.