IntroductionResearch identifying the needs of relatives of patients with an acquired brain injury or malignant brain tumours is emerging, and the importance of relative involvement is widely acknowledged. However, the intention of involvement does not seem to be present in current practice and healthcare professionals’ routines. The complexity of involvement of relatives is comprehensive, and there is a lack of overview of interventions facilitating and enhancing involvement of relatives. This scoping review aims to identify and map the available evidence on interventions facilitating involvement of relatives of patients with acquired brain injury or malignant brain tumour throughout the disease trajectory.Methods and analysisThe proposed scoping review will be performed following the Joanna Briggs Institute’s methodology for scoping reviews. Published and unpublished literature in English, Scandinavian and German from January 2010 to August 2022 will be considered. The searches will be conducted using electronic bibliographic databases. This scoping review will consider studies describing interventions provided by multidisciplinary healthcare professionals. The key aspects of the interventions could, for example, be educational, informational, emotional, social or physical support aiming towards involvement of the relatives. This scoping review will consider all study designs, except for literature reviews of all types and designs. The data will be extracted using a data extraction tool developed to record specific data, including details of authors, year of publication, country, setting, study population, study design and key aspects of the intervention (mode, duration, intensity, provider) and type of primary and secondary outcomes applied to measure the interventions. The results will be presented in tabular form, accompanied by a descriptive summary related to the objective of the present scoping review.Ethics and disseminationThis scoping review is conducted as part of a larger postdoc project, which has been approved by the Danish Data Protection Agency (ID P-2020–547). The results will be disseminated through a peer-reviewed journal and presented at local, national and international conferences on brain injuries and brain cancer.