Background: The benefits of vaccination have been comprehensively proven, however disparities in coverage persist due to poor health system management, limited resources and parental knowledge and attitudes. Evidence suggests that health interventions that engage local parties in communication strategies improve vaccination uptake. As mobile technology is widely used to improve health communication, mobile health (mHealth) interventions might be used to increase coverage. Objective: To conduct a systematic review of the available literature on the use of mHealth to improve vaccination in low and middle income countries with large numbers of unvaccinated children. Methods: In February 2017, MEDLINE, Scopus and Web of Science, and three health organization websites; Communication Initiative Network, TechNet-21, and PATH, were searched to identify mHealth intervention studies on vaccination uptake in 21 countries. Results: Ten peer-reviewed studies and eleven studies from white or grey literature were included. Nine took place in India, three in Pakistan, two each in Malawi and Nigeria, and one each in Bangladesh, Zambia, Zimbabwe and Kenya. Ten peer-reviewed studies and seven white/grey studies demonstrated improved vaccination uptake after interventions, including appointment reminders, mobile phone apps and pre-recorded messages. Conclusions: While the potential for mHealth interventions to improve vaccination coverage seems clear, the evidence for such interventions is not. The dearth of studies in countries facing the greatest barriers to immunization impedes the prospects for evidence-based policy and practice in these settings.