This systematic review explores the methods and approaches to co-producing digital mental health interventions (DMHIs) and identifies barriers and facilitators to this process. The review included 26 studies across 24 DMHIs, highlighting that co-production with stakeholders is often limited to early or final stages of development, contradicting the core principles of co-production. Co-production with stakeholders added value by creating culturally sensitive and acceptable interventions. Challenges included resource constraints, variability in stakeholder suggestions, and power imbalances between stakeholders and researchers. The review emphasizes the importance of involving diverse stakeholders throughout all stages of DMHI development to ensure inclusivity and equality in decision-making. Key findings include the need for larger, more diverse samples, the use of creative methods like 'think aloud' to enhance engagement, and the importance of involving stakeholders in all phases of DMHI development. The review also highlights the need for a standardized framework to guide co-production processes and the importance of addressing power dynamics to ensure equitable participation. Recommendations include involving a diverse stakeholder group, using creative and participatory methods, and ensuring that co-production principles are operationalized in practice. The review underscores the value of co-production in improving the acceptability and effectiveness of DMHIs, and calls for further research to evaluate the efficacy of co-produced frameworks in all stages of DMHI development.This systematic review explores the methods and approaches to co-producing digital mental health interventions (DMHIs) and identifies barriers and facilitators to this process. The review included 26 studies across 24 DMHIs, highlighting that co-production with stakeholders is often limited to early or final stages of development, contradicting the core principles of co-production. Co-production with stakeholders added value by creating culturally sensitive and acceptable interventions. Challenges included resource constraints, variability in stakeholder suggestions, and power imbalances between stakeholders and researchers. The review emphasizes the importance of involving diverse stakeholders throughout all stages of DMHI development to ensure inclusivity and equality in decision-making. Key findings include the need for larger, more diverse samples, the use of creative methods like 'think aloud' to enhance engagement, and the importance of involving stakeholders in all phases of DMHI development. The review also highlights the need for a standardized framework to guide co-production processes and the importance of addressing power dynamics to ensure equitable participation. Recommendations include involving a diverse stakeholder group, using creative and participatory methods, and ensuring that co-production principles are operationalized in practice. The review underscores the value of co-production in improving the acceptability and effectiveness of DMHIs, and calls for further research to evaluate the efficacy of co-produced frameworks in all stages of DMHI development.