Providing specially trained volunteer navigators is one promising strategy for supporting the increasing number of family caregivers who are caring for children living with medical complexity. The objective of this study was to develop consensus on the role and competencies required for volunteer navigators who support caregivers of children living with medical complexity. This was a mixed-method study using modified e-Delphi and focus group methods. In phase 1, a modified e-Delphi survey with 20 family caregivers and a focus group with 4 family caregivers were conducted to develop consensus on their unmet needs and the potential roles of a volunteer to meet those needs. In phase 2, a modified e-Delphi survey was conducted with experts to develop consensus on the volunteer competencies required to meet the roles identified by family caregivers in phase 1. Findings from phase 1 resulted in 36 need-related items over 8 domains: communication, daily life and chores, emotional support, information and knowledge, respite, support with decision-making, and sharing the caregiving experience. Concerns about the volunteer role included the potential lack of commitment in the absence of remuneration, the complexity of the child's condition that was beyond the role of a volunteer, and a preference for support from individuals they knew. Findings from the phase 2 Delphi survey with professionals resulted in 22 competencies, derived from the roles identified in phase 1, that would be required of volunteers who wished to support these family caregivers. This study provides insight into a role for volunteers in meeting the needs of family caregivers of children living with medical complexity. A volunteer with lived experience and adequate preparation can assist with meeting some of these important needs. Further research is required to better understand the feasibility and acceptability of such a role.