Background: Evidenced-based health promotion programmes for youth with intellectual and developmental disabilities (I/DD) are notably absent. Barriers include a lack of understanding of how to adapt existing evidence-based programmes to their needs, maximize inclusion and support mutual goals of health and autonomy. Methods: We undertook a community-engaged process to adapt a school-based nutrition intervention in a residential school for youth with I/DD. Focus groups and interviews with school staff elicited recommendations for adaptation strategies; these were then reviewed by an expert panel. Results: Adaptations were developed to address needs in three categories: food-related challenges among students, adjusting to change and transition and social environment factors. Choice and heterogeneity were overarching themes across the adaptation categories. Conclusions: Future research should consider community-engaged approaches for adaptation so that youth with I/DD can participate and benefit from evidence-based health promotion programmes to their maximum potential.