We examine how strategic HR governance responses shape workplace mental health outcomes and how organizational culture strength conditions these effects at the organizational level. Using the Workplace Mental Health Governance Dataset compiled from internationally standardized sources, we analyze a global sample of 43 medium and large organizations operating formal HR governance systems between 2019 and 2022. We estimate multivariate regression models with interaction terms to assess how mental health policy design, leadership support practices, and employee assistance systems jointly influence psychological wellbeing, absenteeism reduction, productivity stability, and employee retention under varying cultural conditions. The results show that leadership support practices exert the strongest direct effects across outcome dimensions, while policy design provides a necessary structural foundation and assistance systems contribute primarily to recovery and retention. Organizational culture strength significantly amplifies all governance effects by translating formal mechanisms into consistent behavioral outcomes. The contribution lies in advancing the HR MindRisk Governance Model, which specifies a conditional governance architecture explaining why similar HR interventions yield divergent mental health outcomes across organizations and contexts. The findings refine HR governance and occupational health theory and offer policy relevant guidance for aligning governance design, leadership capability, and culture to reduce mental health risk exposure globally.