Low socioeconomic populations, when compared to more affluent groups, are at greater risk of initiating risky behaviours and consequently developing health complications. Health literacy has been identified as a possible means to improve and sustain positive health behaviours, with adolescence being a time point when such behaviours can be embedded. To develop a meaningful health intervention, it has been recommended that relevant stakeholders be included in the design phase. This formative evaluation study was the second phase of co-design of an engaging health literacy intervention 'LifeLab' with, and for, socioeconomically disadvantaged adolescents in Ireland. In Spring 2021, a series of co-design workshops ( = 17) were facilitated with a convenience sample of adolescents from socially disadvantaged areas ( = 22) to gather their perceptions, feedback, and suggested changes on the LifeLab learning activities that had emerged from Phase 1 of the work. The data was analysed using reflexive thematic analysis, resulting in the development of three themes: (i) preferred learning engagement strategies, (ii) practical and logistical considerations and (iii) ideas for LifeLab content. The results highlight the value in adopting a participatory approach, as participants offered an array of suggestions and details to maximise the potential for LifeLab to be contextually relevant and engaging; suggestions which will directly inform the development and implementation of the intervention.