This systematic review synthesized the literature on digital health interventions for the promotion of physical activity (PA) among people with intellectual disabilities and/or autism. From an initial screening of 553 records, 10 studies underwent full-text review. Data were extracted relating to study, intervention, and sample characteristics and PA-related findings. Methodological quality was evaluated using the Crowe Critical Appraisal Tool. There were mixed findings pertaining to the effectiveness of digital health interventions for promoting PA among these populations. Positive results were reported for three of five active-video-game interventions, two of three social-media-based interventions, and one of two e-learning/multicomponent interventions. Digital health interventions can potentially be effective for promoting PA among people with intellectual disabilities and/or autism. However, the large variation in the samples and intervention types and a reliance on pre- and quasi-experimental research designs suggest that inferences should be made with caution and additional research is needed.