Autistic children and adolescents are at high risk of dental disease and experience oral health inequalities. They consistently show high levels of unmet needs in relation to their oral health and access to dental care. There are no systematic reviews that bring together the evidence on the factors that influence oral hygiene behaviours, and access to and provision of dental care for autistic children and adolescents. A systematic search will be carried out in eight international databases and in grey literature of qualitative, quantitative and mixed method research studies from countries with a High Development Index which relate to oral health behaviours, and access to and provision of dental care. Only studies where participants are autistic children and adolescents aged 19 years or under, parents/guardians/caregivers, support staff, or oral health care providers will be included. Quantitative and qualitative data will be synthesized together through data transformation using a convergent integrated approach. Thematic synthesis will be used to carry out an inductive analysis of the data. The findings from the systematic review which this protocol generates will be used in the development of an appropriate local clinic care pathway for autistic children/adolescents and to inform national policies and practices. Prospero registration: CRD 42021248764.