The estimated global disease burden of mental illness is 32.4% of years lived with disability. Mental health is a critical determinant for public health, and government-level action is needed for integration of mental health into public health. But in many low/middle-income countries (LMICs) mental health is absent on the policy agenda, despite up to 90% of people with mental illness lacking treatment. Evidence on cost-effective treatments is available, but translation of research into policy is a 'wicked' problem and often fails. We investigate the inter-relationships of research evidence and mental health policymaking in LMICs and present a framework/advocacy tool to guide and support evidence-based public mental health policymaking. Using a mixed-methods approach, we conducted a systematic review, based on which we developed a provisional framework (EVITA), revised and validated it through expert in-depth interviews. We then empirically tested the EVITA framework against three case studies (provincial, national, global level, South Africa). We collected qualitative data through expert interviews/documentary analysis, coded and analysed the data in NVivo, and finalised the framework and action tool. We identified agenda-setting as a research theory gap in the context of mental health knowledge translation in LMICs. Thus we developed the EVITA framework for evidence-based mental health policy agenda-setting, and validated it against empirical case studies. Our findings suggest that behavioural methods can support interventions to improve research uptake. The EVITA action tool has been theoretically and empirically validated, and includes policy agenda-setting and behavioural methods as a novel, effective mechanisms for improving evidence-based policymaking in public mental health. EVITA has the potential to improve the challenging process of research evidence translation into policy/practice in LMICs, and may be applicable to other neglected health areas/countries. Key messages * The new validated EVITA framework uses agenda-setting and behavioural methods to improve knowledge exchange for better evidence-informed, potentially more effective, public mental health policymaking. * The EVITA action tool helps researchers, policymakers & others to strategically take action for public mental health agenda-setting and advocacy interventions for evidence-based policymaking in LMICs.