INTRODUCTION: Mainstream Australian mental health services are failing Aboriginal young people. Despite investing resources, improvements in well-being have not materialised. Culturally and age appropriate ways of working are needed to improve service access and responsiveness. This Aboriginal-led study brings Aboriginal Elders, young people and youth mental health service staff together to build relationships to co-design service models and evaluation tools. Currently, three Western Australian youth mental health services in the Perth metropolitan area and two regional services are working with local Elders and young people to improve their capacity for culturally and age appropriate services. Further Western Australian sites will be engaged as part of research translation. METHODS AND ANALYSIS: Relationships ground the study, which utilises Indigenous methodologies and participatory action research. This involves Elders, young people and service staff as co-researchers and the application of a decolonising, strengths-based framework to create the conditions for engagement. It foregrounds experiential learning and Aboriginal ways of working to establish relationships and deepen non-Aboriginal co-researchers' knowledge and understanding of local, place-based cultural practices. Once relationships are developed, co-design workshops occur at each site directed by local Elders and young people. Co-designed evaluation tools will assess any changes to community perceptions of youth mental health services and the enablers and barriers to service engagement. ETHICS AND DISSEMINATION: The study has approval from the Kimberley Aboriginal Health Planning Forum Kimberley Research Subcommittee, the Western Australian Aboriginal Health Ethics Committee, and the Curtin University Human Research Ethics Committee. Transferability of the outcomes across the youth mental health sector will be directed by the co-researchers and is supported through Aboriginal and non-Aboriginal organisations including youth mental health services, peak mental health bodies and consumer groups. Community reports and events, peer-reviewed journal articles, conference presentations and social and mainstream media will aid dissemination.