This randomized trial compared the first online parent training program for an evidence-supported executive function intervention for autism to in-person parent training with the same dose and content. Parents of autistic children (8-12 years-old; Full Scale IQ above 70) were randomized to in-person (n = 51) or online (n = 46) training. Training acceptability and feasibility were rated highly by parents, without significant differences between groups. The completion rate was lower for parents in the online versus the in-person training condition, but neither the total time spent with training materials, nor parent and child outcomes differed by condition. Parents reported that training resulted in a reduction in caregiver strain (Cohen's d = 0.66) and modest improvements in child flexibility, emotional control and global EF, but not planning and organization. Dose of parent training had a significant positive effect on child planning and organization problems. These findings did not support the hypothesized superiority of online to in-person training, but they did indicate online is as effective as in-person training at helping parents learn to improve their autistic children's EF abilities and reduce their own experience of parenting strain. Implications included increased access to training for parents who experience barriers to receiving in-person care.