BACKGROUND: People experiencing homelessness (PEH) are known to be at higher risk of adverse health outcomes and premature mortality when compared to the housed population and often face significant barriers when attempting to access health services. This study aimed to better understand the specific health care needs of PEH and the barriers and facilitators associated with their timely and equitable access to health services in the European context. METHODS: We conducted an exploratory cross-national qualitative study involving people with lived experience of homelessness and health and social care professionals in Austria, Greece, Spain, and the UK. A total of 69 semi-structured interviews comprising 15 social care professionals, 19 health care professionals, and 35 PEH were completed, transcribed, and analysed thematically. RESULTS: Findings were organised into three overarching themes relating to the research question: (a) Health care needs of PEH, (b) Barriers to health care access, and (c) Facilitators to health care access. Overall, the general health of PEH was depicted as extremely poor, and mainstream health services were portrayed as ill-equipped to respond to the needs of this population. Adopting tailored approaches to care, especially involving trusted professionals in the delivery of care, was identified as a key strategy for overcoming existing barriers. CONCLUSIONS: The results of this study indicate there to be a high degree of consistency in the health care needs of PEH and the barriers and facilitators associated with their access to health care across the various European settings. Homelessness in itself is recognized to represent an essential social determinant of health, with PEH at risk of unequal access to health services. Changes are thus required to facilitate PEH's access to mainstream primary care. This can also be further complemented by investment in 'in-reach' services and other tailored and person-centred forms of health care. TRIAL REGISTRATION: This study was registered retrospectively on June 6, 2022, in the registry of ClinicalTrials.gov under the number NCT05406687.