Parents of autistic children are at a higher risk for mental health problems, including anxiety, depression, and stress. Cognitive behavior therapy (CBT) that targets children's emotion regulation may have an indirect influence on parent outcomes, especially if they play a supporting role in their child's intervention. However, most CBT interventions have been carried out in highly controlled research settings and there are a few studies that examined parental outcomes after participating in autistic child-focused CBT within a community setting. The current study examined parent outcomes (i.e., mental health problems, mindful parenting, and parenting practices) following a community-based CBT program with concurrent parent involvement for autistic children, as well as associations between changes in parent and child outcomes (i.e., autism symptoms and emotion dysregulation). Participants included 77 parent-child dyads across seven community organizations in Ontario, Canada. Parents reported improved mindful parenting and positive parenting practices post-intervention, and no significant changes in their mental health. Multiple mediation analyses revealed that positive changes in parent outcomes (i.e., mindful parenting and parenting practices) were associated with positive changes in child emotion regulation. These positive changes in parenting practices mediated the relationship between mindful parenting and child emotion regulation. Results suggest that participating in community-based CBT is mutually beneficial for autistic children and their parents, particularly in improving parenting behaviors.