INTRODUCTION: Early evidence confirms lower COVID-19 vaccine uptake in established ethnic minority populations, yet there has been little focus on understanding vaccine hesitancy and barriers to vaccination in migrants. Growing populations of precarious migrants (including undocumented migrants, asylum seekers and refugees) in the UK and Europe are considered to be under-immunised groups and may be excluded from health systems, yet little is known about their views on COVID-19 vaccines specifically, which are essential to identify key solutions and action points to strengthen vaccine roll-out. METHODS: We did an in-depth semi-structured qualitative interview study of recently arrived migrants (foreign-born, >18 years old; <10 years in the UK) to the UK with precarious immigration status between September 2020 and March 2021, seeking their input into strategies to strengthen COVID-19 vaccine delivery and uptake. We used the 'Three Cs' model (confidence, complacency and convenience) to explore COVID-19 vaccine hesitancy, barriers and access. Data were analysed using a thematic framework approach. Data collection continued until data saturation was reached, and no novel concepts were arising. The study was approved by the University of London ethics committee (REC 2020.00630). RESULTS: We approached 20 migrant support groups nationwide, recruiting 32 migrants (mean age 37.1 years; 21 [66%] female; mean time in the UK 5.6 years [SD 3.7 years]), including refugees (n = 3), asylum seekers (n = 19), undocumented migrants (n = 8) and migrants with limited leave to remain (n = 2) from 15 different countries (5 WHO regions). 23 (72%) of 32 migrants reported being hesitant about accepting a COVID-19 vaccine and two (6%) would definitely not accept a vaccine. Participants communicated concerns over vaccine content, side-effects, lack of accessible information in an appropriate language, lack of trust in the health system and low perceived need. A range of barriers to accessing the COVID-19 vaccine were reported and concerns expressed that their communities would be excluded from or de-prioritised in the roll-out. Undocumented migrants described fears over being charged and facing immigration checks if they present for a vaccine. Participants (n = 10) interviewed after recent government announcements that COVID-19 vaccines can be accessed without facing immigration checks remained unaware of this. Participants stated that convenience of access would be a key factor in their decision around whether to accept a vaccine and proposed alternative access points to primary care services (for example, walk-in centres in trusted places such as foodbanks, community centres and charities), alongside promoting registration with primary care for all, and working closely with communities to produce accessible information on COVID-19 vaccination. CONCLUSIONS: Precarious migrants may be hesitant about accepting a COVID-19 vaccine and face multiple and unique barriers to access, requiring simple but innovative solutions to ensure equitable access and uptake. Vaccine hesitancy and low awareness around entitlement and relevant access points could be easily addressed with clear, accessible, and tailored information campaigns, co-produced and delivered by trusted sources within marginalised migrant communities. These findings have immediate relevance to the COVID-19 vaccination initiatives in the UK and in other European and high-income countries with diverse migrant populations. FUNDING: NIHR.