This study explores the impact on its processes and outcomes of including students within a ‘leadership for inclusion’ (LfI) team, which, at the time of the study, was involved in reviewing critically and developing a range of policies and practices that affect young peoples’ experience of belonging and inclusion at a mainstream post primary (PP) school in Ireland. It explores how their participation can impact on group processes and relationships between and among team members and on outcomes, including alterations to policies and practices related to experiences of belonging and inclusion at the school concerned. The study is important and timely in light of the relative paucity of literature and empirical investigation of how adults facilitate student voice and leadership. It draws upon existing research and literature on the value of harnessing student perspectives, particularly those of autistic students, in developing inclusive policy and practice. This evidence is used to set the context for the investigative element of the work, to investigate the impact of involving autistic students in an inclusive leadership team operating in a mainstream PP school. The study employed a sequential case study design that used qualitative data gathering over two phases. It was guided by a conceptual framework. Phase 1 involved five Student Initiative Meetings (SIM) and five Collaborative Leadership Initiative (CLI) team meetings, with autistic students setting the agenda. Phase 2 comprised three focus group discussions with all participants of the CLI to delve deeper into Phase 1 findings and address the research questions. The findings are examined and interpreted within the context of the literature review provided. The study highlighted key processes and outcomes that contribute to positive changes in school culture and practices. Central to these processes were the co-construction of leadership, shared decision-making, and collective responsibility among students, teachers, and leaders. The principal played a pivotal role in promoting inclusive practices, fostering genuine dialogue, and addressing systemic inequities. Teachers experienced empowerment through the development and consistent adoption of effective practices, while students gained a sense of ownership and agency, actively contributing to school decision-making and improvement efforts. Furthermore, it was identified that the creation of safe spaces and authentic student-teacher partnerships was essential for fostering relational care and safety. As a result, the outcomes included enhanced student engagement, motivation, and a greater sense of belonging, which ultimately led to a more connected and inclusive school environment. These changes collectively contributed to the transformation of school culture and the improvement of institutional practices. This study contributes to current knowledge in the areas of collaborative leadership for inclusion at the school level, the mobilisation of learner voices, particularly those of autistic students, and the empowerment of both learners and teachers in driving sustainable change within educational settings. By challenging traditional perspectives and practices, the research highlights the potential to reduce or eliminate ‘soft barrier’, policies and practices that often hinder inclusive education in PP schools and contribute to the marginalisation of autistic and other vulnerable students. The findings provide valuable insights that can inform efforts to create more inclusive and equitable school environments. While the outcomes must be interpreted within the specific context of the study, they offer relevant applications for those interested in fostering inclusive practices in other educational settings. The study thus advances understanding in areas that promote collaborative leadership, elevate the voices of marginalised learners, and empower teachers and students to enact lasting, positive change in school.