In promoting optimal recovery in persons with psychosis, psychological interventions have become a key element of treatment, with cognitive behavioural therapy being widely recommended in clinical practice guidelines. One key area of development has been the trialling of “third wave” cognitive behavioural interventions, which promote mindfulness, acceptance and compassion as means of change. Trials to date have demonstrated encouraging findings, with beneficial effects observed on measures of psychotic symptoms. This meta-analysis evaluated the efficacy of third wave interventions for the treatment of psychosis in randomised controlled trials, with psychotic symptoms as the primary outcome. Overall, 10 studies were included. The primary outcome demonstrated a small but significant effect (g = 0.29) for third wave interventions compared with control post-treatment. Trials of group format mindfulness-based interventions showed larger effects (g = 0.46) than individual acceptance and commitment therapy based interventions (g = 0.08), although methodological differences between trials were noted. Among secondary outcomes, a moderate, significant treatment effect (g = 0.39) was found for depressive symptoms, but no significant effects were found on specific measures of positive and negative symptoms, hallucination distress, or functioning/disability. A moderate effect on mindfulness (g = 0.56) was observed, but not on acceptance. Overall, findings indicate that third wave interventions show beneficial effects on symptoms in persons with psychotic disorders. However, further research is required to determine the efficacy of specific models of treatment.