BACKGROUND: Developing robust evidence is a challenge for researchers working with disadvantaged or vulnerable populations. For example, research shows that young people who have transitioned from out-of-home care (OOHC) to independent adulthood often experience poor long-term outcomes. However, evidence for the aetiology of those outcomes is weak due to methodological limitations such as small sample sizes and a lack of longitudinal data. This paper details the protocol for Navigating Through Life, a study that utilises novel research methods to better understand the pathways and outcomes of young people as they leave OOHC in Western Australia (WA). METHODS: Navigating Through Life is a longitudinal, mixed methods, population-based study. A prospective longitudinal study of young people aged 15-25 years will follow participants' experiences and outcomes over a two-year period. Quantitative and qualitative data is being collected from participants five times over 2 years, using standardised outcome measures and individual interviews. Outcome measures focus on key dimensions of young people's lives (e.g., social inclusion, well-being, resilience, self-determination). Interviews examine important influences and the variable contexts into which young people have transitioned from care. In addition, retrospective population-level data for young people transitioning from OOHC will be obtained from linked Western Australian government administrative records. Using a multitude of data sources, analysis will map pathways and outcomes of young people with care experience, and comparisons will be made with other population groups within WA. DISCUSSION: Navigating Through Life exemplifies a novel utilisation of multiple data sources to research outcomes for vulnerable and difficult to reach populations, and offers insights for other complex mixed-methods longitudinal studies. Results will provide new and more comprehensive data about specific pathways that may be influential to a range of post-care outcomes. Findings will extend evidence to inform better service-delivery models that improve outcomes and reduce disparities for vulnerable young people.