Abstract Background Studying at university is a stressful time for many, which might result in the development of mental health problems. In the first wave of Covid-19, university students in Turkey reported suffering from an elevated level of stress compared to their peers in other countries. Mindfulness-based interventions could provide the means of successfully decreasing the stress level of university students. Moreover, offering interventions via the Internet could be a scalable option to prevent and treat mental health problems, while offering time/place flexibility, anonymity, and cost-effectiveness. Method In a randomized controlled trial of parallel design, the feasibility of a culturally adapted internet- and mobile-based intervention (IMI) (StudiCareM-TR) to promote mindfulness among Turkish-speaking university students was tested. Participants (N = 58) of a public university in Istanbul were randomized into an intervention (IG) vs. waitlist control group (WL). Measurements took place at baseline (t0) and 10 weeks post-randomization (t1). Intervention adherence, acceptance, and potential negative effects were feasibility outcomes. Levels of mindfulness, perceived stress, depression, anxiety, and wellbeing were analyzed in linear regression models to assess the potential efficacy of StudiCareM-TR. All analyses were conducted with the intention-to-treat sample, adjusting for baseline values. Results Based on participants’ feedback, StudiCareM-TR was perceived as acceptable, resulted in few negative effects (n = 7), and yielded improvements in mindfulness (β = 0.70) and presenteeism (β = − 0.61) compared to WL. Secondary outcomes of depression, anxiety, stress, and wellbeing did not show significant improvements. Assessment dropout was 31% (IG: 50%: WL: 89%), and intervention dropout was 45%. Conclusions StudiCareM-TR is feasible and acceptable to use among university students in Turkey and has the potential to improve their mindfulness levels. The intervention should be further developed with a focus on engagement-facilitating features in order to reduce intervention dropouts. Trial registration ID DRKS00024557.