Individuals with intellectual disability (ID) tend to have a sedentary lifestyle, with low physical fitness and an increased risk of chronic diseases. One reason for the prevalence of a sedentary lifestyle is the existence of barriers to participation in physical activity (PA). The purpose of this systematic review is to update knowledge about the perceived barriers of PA participation in individuals with ID. Electronic searches were carried out in the PubMed, Scopus, SPORTDiscus and Web of Science databases, from September 2020 to May 2021, and included articles published between January 2016 and May 2021. The terms used were: “mental retardation”, “intellectual disability”, “intellectual disabilities”, “physical activity”, “motor activity”, “barriers”, “obstacles”, “embarrassment” and “constraint”, in combination with the Boolean operators “AND” or “OR”. After the methodological process, five studies were included for analysis. These studies revealed the existence of several perceived barriers to regular PA participation, which were grouped into five main groups: personal (6 topics), family (4 topics), social (13 topics), financial (1 topic) and environmental (1 topic). The knowledge and identification of participation barriers can be of extreme importance both to institutions and professionals aiming to enhance the participation of individuals with ID in regular PA programs.