Young people in Northern Ireland and the border counties of Ireland face disproportionate mental health challenges, with rates of poor youth wellbeing significantly higher than elsewhere in the United Kingdom and access to support severely limited (Bunting et al., 2020). This paper presents the PEACE of Mind project (funded by the Special European Union Project Body), a cross-community and cross-border youth mental health initiative, as a case study of co-design as inclusive praxis. The paper examines how power dynamics, accessibility and youth agency are activity negotiated on the project rather than assumed. Through two key mechanisms, the Youth Advisory Assembly and co-design sessions, the project demonstrates how meaningful participation requires deliberate, iterative structures operating at the level of citizen power. The project uses a three-component model of inclusive production, characterised through the iterative co-design, the use of accessibility as a structural design, and participant governance. The findings within this paper suggest that the model offers a replicable framework for participatory youth mental health work.