BACKGROUND: Engagement with diverse stakeholders, including policy makers, care providers and service users and communities, is essential for successful implementation of global mental health interventions. Despite being a fundamental factor in the implementation process, evidence about challenges and drivers to stakeholder engagement is limited in the global mental health literature. METHODS: We conducted semi-structured qualitative interviews with 29 recipients of Grand Challenges Canada Global Mental Health funding to assess barriers and drivers to global mental health implementation across a portfolio of projects. We used framework analysis to identify key themes related to implementation barriers and drivers. This paper reports on barriers and drivers to stakeholder engagement, with results related to capacity development and service delivery reported elsewhere in this journal. RESULTS: Barriers and drivers to stakeholder engagement were identified across four themes: (1) Contextual Considerations, (2) Resources, (3) Participation, Uptake and Empowerment, and (4) Stigma. While complex contextual challenges create barriers, mechanisms such as formative research can facilitate a deeper contextual understanding that supports effective implementation planning. Limited financial and human resources and competing priorities can lead to substantial challenges. Investing in and leveraging existing local resources and expertise can help to mitigate these barriers. The challenge of achieving active participation from stakeholders and diverging expectations about the nature of participation were identified as barriers, while providing opportunities for meaningful participation and empowerment acted as drivers. Stigma at the institutional, community and individual level was also identified as a substantial barrier to engagement. CONCLUSION: The findings of this study are relevant to implementers in global mental health. They also have implications for global mental health funding agencies and policy organizations, who can support improved stakeholder engagement by investing in high-quality formative research, supporting capacity building for policy engagement, investing in longer-term funding schemes to support sustainable partnerships and scale-up, thus fostering successful engagement and supporting effective implementation of global mental health innovations.