Background and aim: Human resources are an essential part of any organization especially health care organizations where employees’ competencies are important for the quality of services provided. Successful completion of primary health care projects is a major concern for developing countries due to multiple reasons. This study investigates a missing link between managerial competencies and primary healthcare project success with health workers’ mental health as a mediator and social support as a moderator. Methods and material: The methodology used is quantitative, cross-sectional, and based on primary responses. The PLS Structural Equation Model (SEM) is used for analysis. Results: The results show a positive but weak impact of managerial competencies on the successful completion of healthcare projects in Pakistan. The results further indicate a negative mediation effect, confirming workers lower mental health reduces the positive effect of managerial competencies on project success. Moreover, limited social support for the health workers weakly moderates the relationship between managerial competencies and project success. Conclusion: The outcome suggests that pertinent organizations should design policies to develop managerial competencies and promote an amiable and conducive work environment for health workers. Furthermore, society should accept and provide support to health workers for better project outcomes.