Abstract Background Children and youth with neurodisabilities may experience different challenges during their transition to adulthood, such as pursuing postsecondary education, finding employment, and navigating a new adult health care system. Families, including siblings, have an important role in the process for when youth with neurodisabilities are transitioning to adulthood. Siblings are in a unique position, where they can have different roles such as a friend, mentor, or caregiver. Siblings can offer various supports to their brother or sister with a neurodisability, but they require knowledge and skills for these different supporting roles. Currently, there are limited programs available for siblings to learn how to support their brother or sister with a neurodisability during transition. A first step to develop these sibling support programs is to understand the experiences of siblings of youth with a neurodisability. The purpose of this report is to describe a protocol of a qualitative case study aimed at examining the experiences of siblings including their roles and responsibilities to their brother or sister with a neurodisability during health care transition. Methods An exploratory single case study design will be used. An integrated knowledge translation approach to conducting this study will be used by partnering with the Sibling Youth Advisory Council comprised of siblings who have a brother or sister with a disability throughout all study phases. Participants will include siblings (ages 14–40 years old) with a brother or sister (ages 14–21 years old) with a neurodisability in Ontario, Canada. Semi-structured interviews will be conducted, that will be augmented by photo elicitation and drawings of family tree diagrams. Data will be analyzed using reflexive thematic analysis. Discussion Findings from this study will be shared with siblings, families, researchers, and the broader community. It is important to understand the roles and responsibilities that siblings are choosing to have to support their brother or sister with a neurodisability, and how these roles may change over time as their sibling is growing up and transitions to adulthood. Siblings may require knowledge and skills in these roles, and an understanding about siblings’ experiences in certain roles can help to inform the development of a resource to support siblings during health care transition.