Mothers of children with autism spectrum disorder (ASD) often face high levels of stress. While there have been interventions for parents of children with ASD targeting their parenting skills, there have been fewer studies that aim to target the psychological or physical well-being of the mothers themselves. This study included mothers of children with ASD to cofacilitate acceptance and commitment therapy (ACT) to other mothers of children with ASD. The intervention consisted of one evening session and a full-day workshop, followed by a refresher session 1 month later. Of the 33 mothers that enrolled in the study, 29 attended all three sessions and completed the outcome measures. Significant changes were observed over time in terms of depression, stress, social isolation and physical health scores. Post hoc analyses showed reductions in stress and depression and improvements in physical health which were maintained at follow-up. Results suggest that a brief parent-facilitated ACT group intervention may be effective in improving the mental and physical health of mothers of children with ASD.