Background: The evidence for the effectiveness of e-mental health interventions among ethnic minorities is still preliminary. This mixed methods study investigates the feasibility of a culturally adapted, guided online intervention with the intention to understand how it works and for whom to inform refinement. It also examines its likely effectiveness in reducing suicidal ideation when compared with the treatment as usual. Methods: Turkish migrants with mild to moderate suicidal thoughts were recruited from the general population using social media and newspaper advertisements. The intervention group obtained direct access to a 6-week guided online intervention while participants in the waiting list condition had to wait for 6 weeks. The intervention is based on an existing online intervention and was culturally adapted. Participants in both conditions completed baseline, post-test, and follow-up questionnaires on suicidal ideation (primary outcome), depression, worrying, hopelessness, suicide attempt and self-harm, acculturation, quality of life, and usability. In addition, participants were interviewed to examine the feasibility and mechanisms of action in more depth. The responses were analysed by inductive thematic analysis. Results: Eighty-five people signed up via the study website, and we included 18 (10 intervention, 8 waitlist control). While the therapeutic benefits were emphasised (e.g. feeling connected with the intervention), the feasibility was judged to be low. The main reasons given were not having severe suicidal thoughts and not being represented by the culturally adapted intervention. No suicide attempts were recorded during the study. The suicidal ideation, depression, and hopelessness scores were improved in both groups. Conclusion: Although intended to be a definitive trial, the current study became a feasibility study with process evaluation to understand the components and how they operate. The online intervention was not superior to the control condition. Future studies need to attend ...