Hemiplegia is a form of disability that affects one side of the body and has a prevalence of 0.5–0.7 per 1000 live births. It has consequences not only at the medical level but also on psychological, cognitive, and social aspects, and it prevents children from social participation, especially in sports settings. The studies demonstrating the social impact of sports on the hemiplegic population and, in particular, children, are limited. In addition, previous evaluations of healthcare sports initiatives in the hemiplegic population are not available, and traditional methods of evaluation, which are mostly focused on economic outcomes, are not applicable. Thus, this article employs the social return on investment (SROI) methodology, which is able to determine the socio-economic impacts of an initiative, to evaluate the impact of an innovative ankle–foot orthosis (AFO) for hemiplegic children that was created to promote the possibility of “sports for all”. The model was designed with the involvement of stakeholders in all the phases and with mixed methods to assess the input, outcomes, and impact indicators. The final SROI, computed for a time horizon of three years and with a focus on the Lombardy Region, was equal to 3.265:1. Based on this result, the initiative turned out to be worthy of investment.