BACKGROUND: The UK began delivering its COVID-19 vaccination programme on 8 December 2020, with health and social care workers (H&SCWs) given high priority for vaccination. Despite well-documented occupational exposure risks, however, there is evidence of lower uptake among some H&SCW groups. METHODS: We used a mixed-methods approach-involving an online cross-sectional survey and semi-structured interviews-to gain insight into COVID-19 vaccination beliefs, attitudes, and behaviours amongst H&SCWs in the UK by socio-demographic and employment variables. 1917 people were surveyed- 1656 healthcare workers (HCWs) and 261 social care workers (SCWs). Twenty participants were interviewed. FINDINGS: Workplace factors contributed to vaccination access and uptake. SCWs were more likely to not be offered COVID-19 vaccination than HCWs (OR:1.453, 95%CI: 1.244-1.696). SCWs specifically reported uncertainties around how to access COVID-19 vaccination. Participants who indicated stronger agreement with the statement 'I would recommend my organisation as a place to work' were more likely to have been offered COVID-19 vaccination (OR:1.285, 95%CI: 1.056-1.563). Those who agreed more strongly with the statement 'I feel/felt under pressure from my employer to get a COVID-19 vaccine' were more likely to have declined vaccination (OR:1.751, 95%CI: 1.271-2.413). Interviewees that experienced employer pressure to get vaccinated felt this exacerbated their vaccine concerns and increased distrust. In comparison to White British and White Irish participants, Black African and Mixed Black African participants were more likely to not be offered (OR:2.011, 95%CI: 1.026-3.943) and more likely to have declined COVID-19 vaccination (OR:5.550, 95%CI: 2.294-13.428). Reasons for declining vaccination among Black African participants included distrust in COVID-19 vaccination, healthcare providers, and policymakers. CONCLUSION: H&SCW employers are in a pivotal position to facilitate COVID-19 vaccination access, by ensuring staff are aware of how to get vaccinated and promoting a workplace environment in which vaccination decisions are informed and voluntary.