Stigma attached to autism spectrum disorder (ASD) is prevalent, but few studies have examined its psychological impact on parents of children with ASD and the potential protective factors in this family context. The present study aimed to test the associations of public stigma and courtesy stigma with depression, anxiety, and caregiving burden among parents of children with ASD and to explore whether trait mindfulness would moderate these associations. Cross-sectional questionnaire data were collected from 424 parents of children with ASD residing in Hong Kong, China. Hierarchical regressions revealed significant interactions between public stigma and trait mindfulness and between courtesy stigma and trait mindfulness in predicting depression, anxiety, and caregiving burden. Our findings contributed to the theoretical literature by highlighting the adverse impact of both public stigma and courtesy stigma on the mental health and caregiving experience of parents of children with ASD, as well as the potential protective effects of trait mindfulness in such processes. Our findings also had important practical implications for the design of effective interventions for this stigmatized group of families.