<jats:p> 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. </jats:p><jats:p> Trial Registration: clinicaltrials.gov Identifier: NCT02708069 </jats:p><jats:sec><jats:title>Lay Abstract</jats:title><jats:p> This study compared the first online parent training program for executive function intervention for autism to in-person parent training on the same content. Participants were parents of autistic children, who were between 8 and 12 years of age and did not have intellectual disability. Parents were randomized to the in-person ( n = 51) or online ( n = 46) training conditions. Both trainings were developed with stakeholder (parents and autistic people) guidance. In this trial, most parents reported that they liked both trainings and that they were able to implement what they learned with their children. Parents in both groups spent equivalent amounts of time (about 8 hours) with the training materials, but while 94% of parents in the in-person training attended both parent trainings, only 59% of parents in the online group completed all 10 online modules. Parents reported that it was difficult to stay motivated to complete the online trainings over the 10-week trial. Parent and child outcomes did not differ significantly between the groups. Overall, parents reported that the trainings resulted in a reduction in their own parenting strain and improvements in their child’s flexibility, emotional control, and global executive function, but not planning and organization. These findings indicated brief in-person and online training can help parents learn to support and improve their autistic children’s executive function abilities, reducing their own experience of parenting strain. The finding that the online training was equivalent to the in-person trainings is important because it is accessible to parents who encounter barriers to in-person care. </jats:p></jats:sec>