IntroductionDespite higher incidence of brain injury among Aboriginal compared with non-Aboriginal Australians, suboptimal engagement exists between rehabilitation services and Aboriginal brain injury survivors. Aboriginal patients often feel culturally insecure in hospital and navigation of services post discharge is complex. Health professionals report feeling ill-equipped working with Aboriginal patients. This study will test the impact of a research-informed culturally secure intervention model for Aboriginal people with brain injury.Methods and analysisDesign: Stepped wedge cluster randomised control trial design; intervention sequentially introduced at four pairs of healthcare sites across Western Australia at 26-week intervals.Recruitment: Aboriginal participants aged ≥18 years within 4 weeks of an acute stroke or traumatic brain injury.Intervention: (1) Cultural security training for hospital staff and (2) local, trial-specific, Aboriginal Brain Injury Coordinators supporting participants.Primary outcome: Quality-of-life using EuroQOL-5D-3L (European Quality of Life scale, five dimensions, three severity levels) Visual Analogue Scale score at 26 weeks post injury. Recruitment of 312 participants is estimated to detect a difference of 15 points with 80% power at the 5% significance level. A linear mixed model will be used to assess the between-condition difference.Secondary outcome measures: Modified Rankin Scale, Functional Independence Measure, Modified Caregiver Strain Index, Hospital Anxiety and Depression Scale at 12 and 26 weeks post injury, rehabilitation occasions of service received, hospital compliance with minimum care processes by 26 weeks post injury, acceptability of Intervention Package, feasibility of Aboriginal Brain Injury Coordinator role.Evaluations: An economic evaluation will determine the potential cost-effectiveness of the intervention. Process evaluation will document fidelity to study processes and capture changing contexts including barriers to intervention implementation and acceptability/feasibility of the intervention through participant questionnaires at 12 and 26 weeks.Ethics and disseminationThe study has approvals from Aboriginal, university and health services human research ethics committees. Findings will be disseminated through stakeholder reports, participant workshops, peer-reviewed journal articles and conference papers.Trial registration numberACTRN12618000139279.