BackgroundDirect support professionals play an important role in facilitating physical activity support for people with intellectual disabilities (ID). This study examined how the characteristics of people with ID and the characteristics of direct support professionals are related to the professionals' behaviour when supporting people with ID in physical activity.MethodsA cross‐sectional approach was used. Direct support professionals (n = 217) who support people with ID completed a self‐report questionnaire, which aimed to measure the components that produced behaviour when providing physical activity support for people with ID. Associations with the characteristics of people with ID and the characteristics of the professionals were analysed using multivariate linear regression models.ResultsThe results demonstrate that the professionals' characteristics – such as age, workplace and training – were related to the variance in the components that theoretically produced the direct support professionals' behaviour. The characteristics of the people with ID did not contribute to the variance in the direct support professionals' behaviour.ConclusionsThe findings suggest that professional characteristics are the dominant reasons for the differences observed in the capability, opportunity and motivation of direct support professionals to provide physical activity support. This study also underscores the need for integrated training programmes to help direct support professionals promote physical activity in people with ID.