Caregivers with an autistic child often experience stigma, which can lead to detrimental mental health consequences. Affiliate stigma is the internalization of, and psychological responses to, stigma experienced due to an individual’s association with a person who is stigmatized. Social support has been shown to mediate the relationship between affiliate stigma and depression in caregivers of special needs children. However, research on social support as a moderator of this relationship in autistic children has not been completed. We examined the associations between affiliate stigma, social support, and depression as well as the moderating role of social support. Using online questionnaires, 110 caregivers of autistic children reported their child’s autistic traits, affiliate stigma, perceived social support and depressive symptoms. A moderated regression was run to determine if social support significantly impacted the association between affiliate stigma and depression. Affiliate stigma was positively associated with depressive symptoms and social support was negatively associated with depressive symptoms. The moderating effect of social support on the relationship between affiliate stigma and depressive symptoms was not significant. Upon separating the social support variable into family, significant other, and friend subgroups, no additional significant moderators were found. This is one of the first studies to investigate affiliate stigma in North America and demonstrates that affiliate stigma is not only experienced by parents of autistic children but is significantly associated with depression. Clinicians working with these parents might focus on overcoming affiliate stigma to potentially ameliorate their client’s depression.