BACKGROUND: People experiencing homelessness faced unique challenges during the COVID-19 pandemic, including changes to accommodation availability, societal restrictions impacting access to essentials like food, and services moving to remote access. There is a paucity of in-depth qualitative research exploring how the pandemic affected this population, which this research aims to address. METHODS: 33 semi-structured qualitative interviews (22 with people who experienced homelessness during the pandemic and 11 with homelessness sector service providers) were done in the UK between April 26, 2021, and Jan, 25, 2022. Ethical approval was granted by the University College London research ethics committee (Project ID: 14895/005) and all participants provided informed consent. Interviews were audio-recorded, transcribed, and analysed using reflexive thematic analysis utilising NVivo software. Four interviews were coded by two researchers for consistency of codes. FINDINGS: In our sample of people experiencing homelessness, 11 (50%) were female, 13 (59%) White British, all were aged between 24 and 59 years, and all had lived in hostels or hotels, with friends or family, or on the streets during the pandemic. Providers interviewed worked for varied services, including support charities, housing, and addiction services. Four key themes were identified: understanding of and adherence to COVID guidelines; changes to accommodation and experiences of "Everyone In" (a government initiative in which people sleeping on the street or in accommodation where it was difficult to self-isolate were provided emergency accommodation); living through a pandemic while navigating homelessness; and, adaptations to service provision for people experiencing homelessness. INTERPRETATION: Policy makers and public health communicators must learn from people experiencing homelessness to maximise effectiveness of future public health strategies. Housing providers and support services should recognise the implications of imposing a scarcity of choice on people who need accommodation during a public health emergency. The loss of usual support was destabilising for people experiencing homelessness, triggering a need to adopt survival tactics which negatively influence their health. Although this research was limited by the possibility that views expressed might differ from those unwilling or unable to participate, it does highlight successes and difficulties in supporting people experiencing homelessness during the COVID-19 pandemic and informs planning for similar public health events. FUNDING: Nuffield Foundation, Wellcome Trust.