BACKGROUND: End stage kidney disease (ESKD) is associated with many losses, subsequently impacting mental wellbeing. Few studies have investigated the efficacy of psychosocial interventions for people with ESKD and none exist for Indigenous people, a population in which the ESKD burden is especially high. METHODS: This three-arm, waitlist, single-blind randomised controlled trial examined efficacy of the Stay Strong App in improving psychological distress (Kessler distress scale; K10), depressive symptoms (adapted Patient Health Questionnaire; PHQ-9), quality of life (EuroQoL; EQ. 5D) and dialysis adherence among Indigenous Australians undergoing haemodialysis in central and northern Australia (Alice Springs and Darwin), with follow up over two 3-month periods. Effects of immediate AIMhi Stay Strong App treatment were compared with those from a contact control app (The Hep B Story) and treatment as usual (TAU). Control conditions received the Stay Strong intervention after 3 months. RESULTS: Primary analyses of the full sample (N = 156) showed statistically significant decreases in K10 and PHQ-9 scores at 3 months for the Hep B Story but not for the Stay Strong app or TAU. Restricting the sample to those with moderate to severe symptoms of distress or depression (K10 > =25 or PHQ-9 > =10) showed significant decreases in K10 and PHQ-9 scores for both Stay Strong and Hep B Story. No significant differences were observed for the EQ-5D or dialysis attendance. CONCLUSIONS: Findings suggest that talking to people about their wellbeing and providing information relevant to kidney health using culturally adapted, locally relevant apps improve the wellbeing of people on dialysis. Further research is required to replicate these findings and identify active intervention components. TRIAL REGISTRATION: ACTRN12617000249358 ; 17/02/2017.