Children with autism spectrum disorder (ASD) and intellectual disabilities (IDs) are more vulnerable to experiencing anxiety disorders. Parental involvement in intervention is crucial for successful management of the interventions in the population of people with ASDs. This article describes the design and evaluation of parenting programme for anxiety disorders in children and young people with ASD and ID. In phase 1 semi-structured interviews were conducted to explore management strategies for anxiety at home and in school settings. A total of 34 participants (14 parents, 20 teachers) participated in the interviews. A Delphi process was conducted with health professionals to develop consensus on appropriate anxiety interventions. In phase 2 the intervention programme was implemented by seven parents who also participated in focus group to evaluate the developed programme. A parental programme, calm child programme (CCP), was developed, implemented and evaluated. The evaluations show significant decrease in children's anxiety as a result of implementing the programme. This study contributes further evidence to parental involvement in interventions for children and young people with ASD and IDs. The CCP is a useful and cost-effective approach in enabling parents to provide anxiety interventions in a home setting.