Aim To evaluate the feasibility of a structured nurse‐led supportive intervention and its effects on family caregivers in end‐of‐life care at home.Background Family caregivers are crucial in end‐of‐life care. They may experience burden due to the responsibilities associated with caregiving. Some family caregivers feel insufficiently prepared for their caregiver role. Nurses have a unique position to provide supportive interventions at home to reduce caregivers’ burden and improve preparedness. However, few nurse‐led interventions are available to support family caregivers in end‐of‐life care at home. Design We will perform a cluster randomized controlled trial. The clusters consist of twelve home care services, randomly assigned to the intervention group or the control group. Methods The study population consists of family caregivers of patients in the last phase of life. In the intervention group, nurses will systematically assess the supportive needs of family caregivers, using an assessment tool and the method of clinical reasoning. Family members of the control group receive care as usual. Primary outcome is burden measured by the Self‐Rated Burden Scale. Secondary outcomes are preparedness for caregiving, caregiving reactions and acute (hospital) admissions of the patient. In addition, the feasibility of the intervention will be evaluated. The study was funded in October 2016 and was ethically approved in April 2019. Impact Findings from this study will contribute to the scientific and practical knowledge of nursing interventions to support family caregivers in end‐of‐life care. Trial registration The Netherlands Trial Register (NL7702)