Leadership support has been identified as an essential component of successful workplace health promotion (WHP) programs. However, there is little research in this area and even less theoretical conceptualization on ways in which leadership support for WHP is related to improved employee wellbeing. In this paper, we developed and tested a model of leadership support for WHP and employee wellbeing outcomes using employer and employee data gathered from 71 South African organizations. A theoretical model based on social exchange theory was developed. It was hypothesized that perceptions of company commitment to health promotion mediates the relationship between leadership support, the provision of WHP facilities and employee wellbeing. A hierarchical structural equation modeling technique was used to test the model. We determined that leaders’ support for WHP was important insofar as they also provided health promotion facilities to their employees. No direct relationship was found between leadership support alone and employee wellbeing.