SUMMARY: Stress and mental health are among the biggest causes of sickness absence in the UK, with the Social Work and Social Care sectors having among the highest levels of stress and mental health sickness absence of all professions in the UK. Chronically poor working conditions are known to impact employees' psychological and physiological health. The spread of the COVID-19 pandemic has affected both the mode and method of work in Social Care and Social Work. Through a series of cross-sectional online surveys, completed by a total of 4,950 UK Social Care and Social Workers, this study reports the changing working conditions and well-being of UK Social Care and Social Workers at two time points (phases) during the COVID-19 pandemic. FINDINGS: All working conditions and well-being measures were found to be significantly worse during Phase 2 (November-January 2021) than Phase 1 (May-July 2020), with worse psychological well-being than the UK average in Phase 2. Furthermore, our findings indicate that in January 2021, feelings about general well-being, control at work, and working conditions predicted worsened psychological well-being. APPLICATIONS: Our findings highlight the importance of understanding and addressing the impact of the pandemic on the Social Care and Social Work workforce, thus highlighting that individuals, organizations, and governments need to develop mechanisms to support these employees during and beyond the pandemic.