Developing and nurturing resilience is critical to the social and emotional wellbeing (SEWB) of Indigenous Australian adolescents and their continuing life trajectories. The attendance of many Indigenous adolescents from remote communities at boarding schools creates a need to prioritise and proactively create opportunities that build and nurture student resilience. This requires sustainable and multi-dimensional school-wide approaches. Despite this need, there are no documented SEWB or resilience building approaches for Australian Indigenous students who attend boarding schools. We describe the use of participatory action research to develop and implement a two-year STEP-UP intervention with boarding schools, designed to create supportive environments for improving psychosocial resilience and wellbeing of remote-living Indigenous students. The intervention consisted of three components implemented annually across eight schools: a site-specific STEP-UP action plan; staff capacity development; and an annual Schools and Communities Conference. Thematic analysis of a systematic literature review, documented action planning, conference group processes, resilience theory and survey findings from the associated broader resilience study resulted in the identification of six resilience building domains: valuing culture and identity; developing cultural leadership; nurturing strong relationships; building social and emotional skills; creating safe, supportive environments; and building staff capacity. These domains became the resulting framework for STEP-UP planning and enabled focused examination of practices and future planning. Learnings from the intervention process suggest principles to consider when designing interventions: utilising a strengths-based approach; design responsiveness; collaborative partnerships; institutional capacity; and sustainability. A resilience toolkit website was developed to enable knowledge translation and sustainability beyond the study.