BACKGROUND: Medical school typically presents students with a combination of academic and personal stressors that may lead to substandard mental health wellbeing. Meditation practices such as mindfulness facilitate a greater awareness of one's thoughts and feelings, thereby decreasing emotional reactivity. The use of mindfulness-based interventions delivered online has considerable potential in fostering self-care and helping medical students to handle mental health challenges. We examined the available evidence on the use of online mindfulness interventions in order to determine whether they are feasible and effective for improving medical students' mental health. METHODS: We performed a systematic review guided by PRISMA guidelines and utilised the following databases: ProQuest, Medline, PubMed, PsycINFO, Web of Science, IEEE Explore, Cochrane, and CINAHL. The key search terms used include mindfulness, cognitive behavioural therapy, acceptance and commitment therapy, online, web, virtual, internet cyber, app, medical students, residency students, and residents. English-language articles published in the last ten years that described online interventions for medical students or residents were included in the review. RESULTS: Two studies describing the impact of online mindfulness interventions on medical students' mental health were identified. Research in this domain is nascent; available qualitative and quantitative evidence suggests benefits in self-compassion, perceived stress, cognitive skill use, mindfulness, creating coping mechanisms, and greater awareness of emotions and feelings. There was no evidence of the effectiveness of online mindfulness interventions on depression, anxiety and burnout. There was, however, general low program usage and participation tended to diminish near the conclusion of the interventions. CONCLUSIONS: The evidence found in the systematic review exhibits the potential for online mindfulness interventions to be effective in addressing some mental health challenges of medical students. There was insufficient evidence to support the use of online mindfulness interventions for burnout, depression, and anxiety. Longitudinal studies with randomised controlled trials are required to generate stronger and robust evidence.