Exercise interventions are identified as effective treatments for children not meeting developmental milestones. This systematic review synthesizes research regarding exercise interventions that involved social participatory elements, for children with complex developmental needs. Academic Search Complete, CINAHL, Emcare, Proquest Theses and Dissertations, MEDLINE, and Google Scholar were searched systematically for relevant studies. Peer-reviewed studies meeting the review aim and published between 2000 and 2021 in English, were included. Methodological quality of 49 eligible studies (47 controlled trials, two mixed methods, total of 2355 participants) was appraised using the Mixed Methods Appraisal Tool. Narrative synthesis identified two groups of studies: Group 1 incorporated intentional social participatory elements; Group 2 likely involved incidental social participation. Most studies were of moderate to low methodological quality. Few measured impacts of interventions upon total physical activity levels. Short-term improvements in physical outcomes – particularly motor skills – were most frequently reported and were the main benefit of social exercise interventions for children with complex developmental needs, for which evidence exists. Further rigorous, longitudinal research is needed to assess social, psychological, and executive function outcomes of social exercise interventions in this population. Such interventions should incorporate booster sessions to provide children with greater opportunity to meet developmental milestones.