Background: The protective effects of social support for caregiver mental health are well documented, however the differential impact of support providers (partner, child, family, siblings, friends, professionals) and types (perceived, received) remain unclear. Methods: Observational data from 21 independent studies, involving a pooled sample of 2273 parents, stepparents and grandparents of children (aged ≤ 19) with autism spectrum disorder (ASD) were examined. Pearson's r, publication bias and heterogeneity were calculated using random effects modelling. Results: Significant associations were noted between lowered depressive symptoms and positive sources of support, regardless of support type. Conclusions: Parental mental health can be enhanced by strengthening close personal relationships alongside connections with formal support services. Longitudinal research is needed to explore support need and perceived helpfulness over time.