Background: Research suggests that sport facilitates belonging for diverse athletes. This scoping review characterizes literature on sport participation and belonging for young adults with intellectual and developmental disabilities. Materials and Methods: A search of five databases identified 17,497 articles. Selected articles (N = 39) underwent data extraction and analysis guided by a theoretical framework of belonging, outlining four processes through which belonging is experienced by individuals with intellectual and developmental disabilities. Results: Articles originated from developed countries and in the context of Special Olympics (N = 17). Studies commonly used qualitative interviews with proxy respondents. While all studies described at least one belonging process, only 11 studies applied the term "belonging," and no study defined the construct. Conclusion: Belonging is not well-conceptualized in sports literature for athletes with intellectual and developmental disabilities. Understanding belonging through sport participation for this population may inform sport-based policies and programming.