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 indications for its effectiveness in reducing suicidal ideation when compared with the treatment as usual. Methods: Turkish migrants (first and second generation) 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 weeks 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: A total of 85 people signed up via the study website and 18 (10 intervention, 8 waitlist control) were included. 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: The online intervention, as might be expected in a small feasibility study, was not superior to the control condition. Future studies need to attend the implementation issues raised including measures of stigma, acculturation, careful cultural adaptations alongside more attention to coaching and relational support. They should also consider how to improve engagement alongside selection of those who are motivated to use online interventions and offer alternatives for those who are not. Trial registration: NTR5028. Registered 1 March 2015, https://www.trialregister.nl/trial/4926