Aims: To evaluate the effectiveness of psychological interventions in reducing stress, depression and anxiety among parents of children and adolescents with developmental disabilities. Design: A systematic review and a meta-analysis. Data sources: Seven electronic databases (CINAHL, CENTRAL, EMBASE, ProQuest Dissertation and Theses, PsycINFO, PubMed and Scopus) were searched from each database's point of inception to December 2018. Review methods: Quality appraisal was conducted using the Cochrane Risk of Bias Tool. Data were analysed using Review Manager 5.3. The overall quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation system. Results: A total of 18 studies were included in this review. Eleven studies were involved in a meta-analysis and the remaining seven studies were summarized narratively. The meta-analysis found that psychological interventions significantly reduced parental stress at postintervention but not at 3-6 months' postintervention. Inconclusive evidence was found for the effectiveness of psychological interventions in reducing parental depression and anxiety. Conclusion: Psychological interventions appeared to reduce parental stress temporarily. Healthcare professionals can offer varied psychological interventions for parents to choose from. Policymakers can ease accessibility and affordability for parents to attend interventions. Impact: Psychological interventions were found to have short-term effects in reducing parental stress. Inconclusive evidence was found for the effectiveness of psychological interventions in reducing parental depression and anxiety. Healthcare professionals should ensure that knowledge is transmitted to parents when delivering their interventions. Policymakers worldwide should ensure that parents of children and adolescents with developmental disabilities can attend interventions by making them accessible and affordable.