AimsTo investigate the level of adoption of evidence‐based family engagement and support during end‐of‐life cancer care and subsequent bereavement and its contextual facilitators and barriers from health professionals' perspectives, and to explore differences between professional groups.DesignContextual analysis using an online cross‐sectional survey.MethodsThis study was conducted in four Swiss hospitals and three home care oncology and palliative care services. Non‐parametric testing was used to investigate the level of adoption and differences between nurses, physicians, occupational‐ and physiotherapists and psychosocial professionals (chaplains, onco‐psychologists and social workers). The STROBE checklist for cross‐sectional studies was followed.ResultsThe majority of the 111 participating health professionals were nurses. Adoption was statistically significantly higher during end‐of‐life care than bereavement, with nurses and physicians reporting higher levels than the other professional groups. Guidance on end‐of‐life family care was available in about half of the cases, in contrast to a quarter for bereavement care. Self‐perceived knowledge, skills and attitudes were moderate to high, with nurses and physicians reporting higher levels than others, except for general skills in working with families. Organisational structures were experienced as rather supportive, with the psychosocial group appraising the organisational context as significantly less conducive to fully implementing end‐of‐life and bereavement care than others, particularly during the end‐of‐life phase.ConclusionEvidence‐based family engagement and support were better adopted during end‐of‐life care than bereavement. Overall, nurses and physicians felt better enabled to care for families compared to other professional groups.Patient or Public ContributionNo patient or public contribution.Protocol registrationhttps://osf.io/j4kfh.Implications for the profession and/or patient careImplementation and quality improvement efforts should focus particularly on the bereavement phase and be tailored to professional groups.ImpactThe findings show that evidence‐based family engagement and support practices during end‐of‐life were rather well adopted in contrast to subsequent bereavement care, with nurses and physicians better enabled than other professionals to provide care. A better understanding of health professionals' contributions and roles in family care is important to build interprofessional capacity for evidence‐based end‐of‐life and bereavement support.Reporting MethodThe STROBE checklist for reports of cross‐sectional studies was followed (von Elm et al., 2007).