Family caregivers make employment adjustment to fulfill caregiving responsibility. However, the studies on the family caregivers' mental health outcomes associated with their employment adjustment are limited. This study utilized the role theory and stress process model of caregiving to examine the relationship between employment adjustment and mental health outcomes among family caregivers, and to test family-to-work role conflict as a mediator and workplace support as a moderator in this relationship. Data (n = 1,696) were drawn from the 2012 Canada General Social Survey: Caregiving and Care Receiving. Findings suggest that employment adjustment is significantly associated with negative mental health outcomes including worse self-rated mental health and higher life stress level. In addition, family-to-work role conflict mediates between employment adjustment and mental health outcomes, with the mediating effect as significant at all levels of workplace support and as weak with increasing workplace support. The findings highlight the role of family-to-work role conflict in understanding the influence of employment adjustment on family caregiver's mental health, and the implication of workplace support on promoting caregiver-friendly workplace culture to alleviate family-to-work role conflict thereby resulting in better mental health outcomes.