Children with autism spectrum disorder (ASD) are reported to participate less in everyday activities, and their parents face stigma on account of having a child with ASD, which they often internalize as affiliate stigma. Studies have examined the impact of affiliate stigma on parents’ psychological well-being and social behaviors, but little is known about how affiliate stigma impacts their children’s activity participation. This study aimed to investigate the relationship between parents’ affiliate stigma and activity participation of their children with ASD. Sixty-three parents of children with ASD (aged 2–6 years) were recruited. They completed questionnaires, which captured affiliate stigma, their child’s participation (frequency and involvement) in home, preschool, and community activities, and demographic characteristics. Results indicated that these parents had a moderate level of affiliate stigma, which did not correlate with the frequency of their children’s participation in activities. However, the parents’ affiliate stigma was found to have negative impacts on their children’s involvement in overall community participation and participation in one particular activity at home. The findings highlight the importance of destigmatization of parents of children with ASD in order to promote their children’s participation in community activities.