ObjectiveTo determine the extent and nature of social media use in migrant and ethnic minority communities for COVID-19 information, and implications for preventative health measures including vaccination intent and uptake.DesignA systematic review of published and grey literature following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelinesEligibility Criteria for study selectionGlobal research reporting the use of social media by migrants and/or ethnic minority groups in relation to COVID-19.Data extractionWe extracted data on key outcomes, study design, country, population under study, and sample size.Results1849 unique records were screened, and 21 data sources included in our analysis involving migrant and ethnic minority populations in the UK, US, China, Jordan, Qatar, and Turkey. We found evidence of consistent use of a range of social media platforms for COVID-19 information in some migrant and ethnic minority populations (including WeChat, Facebook, WhatsApp, Instagram, Twitter, YouTube), which may stem from difficulty in accessing COVID-19 information in their native languages or from trusted sources. There were positive and negative associations with social media use reported, with some evidence suggesting circulating misinformation and social media use may be associated with lower participation in preventative health measures, including vaccine intent and uptake, findings of which are likely relevant to multiple population groups.ConclusionsSocial media platforms are an important source of information about COVID-19 for some migrant and ethnic minority populations. Urgent actions and further research are now needed to better understand the use of social media platforms for accessing health information by different population groups – particularly groups who are marginalised from health systems – effective approaches to tackling circulating misinformation, and to seize on opportunities to make better use of social media platforms to support public health communication and improve vaccine uptake.RegistrationThis study has been registered with PROSPERO (CRD42021259190).