The present study examined the longitudinal associations of parents’ discrimination experiences with children’s internalizing and externalizing symptoms among families of autistic children and tested whether these associations would be mediated by parental depression, harsh parenting, and coparenting conflict. On three occasions across 2 years (i.e. T1, T2, and T3), 441 parents of autistic children from Hong Kong, China, provided questionnaire data. Path analyses showed that parents’ discrimination experiences at T1 had significant direct effects on parental depression, harsh parenting, and coparenting conflict at T2, which, in turn, had significant direct effects on children’s internalizing and externalizing symptoms at T3. Bootstrap analyses further demonstrated that parents’ discrimination experiences at T1 had significant indirect effects on children’s internalizing and externalizing symptoms at T3 via parental depression, harsh parenting, and coparenting conflict at T2. Theoretically, our findings elucidate how parents’ discrimination experiences may longitudinally heighten children’s internalizing and externalizing symptoms by adversely affecting parental well-being and parent–child and inter-parental relationships. Practically, our findings highlight the importance of designing and implementing community-based stigma reduction programs and family-based stigma coping interventions to reduce parents’ discrimination experiences and associated adverse outcomes on well-being, parenting, marriage, and child development. Lay abstract Although many parents of autistic children are routinely discriminated against, the potential impact of this discrimination on their parenting processes and child-rearing outcomes has seldom been investigated. The present study addressed this gap in the literature by examining the longitudinal associations of parents’ discrimination experiences with children’s internalizing and externalizing symptoms among families of autistic children and testing whether these associations would be mediated by parental depression, harsh parenting, and coparenting conflict. On three occasions across 2 years (i.e. T1, T2, and T3), 441 parents of autistic children from Hong Kong, China, provided questionnaire data. Path analyses showed that parents’ discrimination experiences at T1 had significant direct effects on parental depression, harsh parenting, and coparenting conflict at T2, which, in turn, had significant direct effects on children’s internalizing and externalizing symptoms at T3. Bootstrap analyses further demonstrated that parents’ discrimination experiences at T1 had significant indirect effects on children’s internalizing and externalizing symptoms at T3 via parental depression, harsh parenting, and coparenting conflict at T2. Our findings have important theoretical contributions and significant practical implications. Theoretically, our findings elucidate how parents’ discrimination experiences may longitudinally heighten children’s internalizing and externalizing symptoms by adversely affecting parental well-being and parent–child and inter-parental relationships. Practically, our findings highlight the importance of designing and implementing community-based stigma reduction programs and family-based stigma coping interventions to reduce parents’ discrimination experiences and associated adverse outcomes on well-being, parenting, marriage, and child development.