BACKGROUND: Many people move in and out of hospital in the last few weeks of life. These care transitions can be distressing for family members because they signify the deterioration and impending death of their ill relative and forthcoming family bereavement. Whilst there is evidence about psychosocial support for family members providing end-of-life care at home, there is limited evidence about how this can be provided in acute hospitals during care transitions. Consequently, family members report a lack of support from hospital-based healthcare professionals. METHODS: The aim of the study was to implement research evidence for family support at the end-of-life in acute hospital care. Informed by Participatory Learning and Action Research and Normalization Process Theory (NPT) we co-designed a context-specific intervention, the Family-Focused Support Conversation, from a detailed review of research evidence. We undertook a pilot implementation in three acute hospital Trusts in England to assess the potential for the intervention to be used in clinical practice. Pilot implementation was undertaken during a three-month period by seven clinical co-researchers - nurses and occupational therapists in hospital specialist palliative care services. Implementation was evaluated through data comprised of reflective records of intervention delivery (n = 22), in-depth records of telephone implementation support meetings between research team members and co-researchers (n = 3), and in-depth evaluation meetings (n = 2). Data were qualitatively analysed using an NPT framework designed for intervention evaluation. RESULTS: Clinical co-researchers readily incorporated the Family-Focused Support Conversation into their everyday work. The intervention changed family support from being solely patient-focused, providing information about patient needs, to family-focused, identifying family concerns about the significance and implications of discharge and facilitating family-focused care. Co-researchers reported an increase in family members' involvement in discharge decisions and end-of-life care planning. CONCLUSION: The Family-Focused Support Conversation is a novel, evidenced-based and context specific intervention. Pilot implementation demonstrated the potential for the intervention to be used in acute hospitals to support family members during end-of-life care transitions. This subsequently informed a larger scale implementation study. TRIAL REGISTRATION: n/a.