Background <p>Adolescents and young adults (AYAs) aged 10–24 years in Sub-Saharan Africa (SSA), including rural Uganda, frequently exhibit low nutrition literacy and poor diet quality, increasing their risk of malnutrition and diet-related non-communicable diseases. Many nutrition interventions are developed in high-income or school-based settings, limiting their relevance for low-income, rural, and out-of-school populations. Context-specific, community-anchored interventions deliverable through existing community health systems remain scarce. This study systematically adapted an adolescent nutrition intervention originally developed in Burkina Faso for household-level delivery in rural Uganda.</p> Methods <p>This participatory action research applied the six-step Intervention Mapping (IM) protocol, guided by the Socio-Ecological Model (SEM) and Social Cognitive Theory (SCT). Step I involved a mixed-methods needs assessment to identify behavioural and environmental determinants. A multi-stakeholder planning group comprising AYAs, parents, community health workers (CHWs), government representatives, and technical experts conducted the adaptation through six iterative design workshops using participatory approaches, including free listing, pile sorting, ranking, and consensus discussions. Steps II–III developed the logic model of change and an SCT-informed theory of change. Steps IV–V co-produced context-specific adaptations in intervention content and delivery strategies, and Step VI developed the evaluation plan.</p> Results <p>The needs assessment informed a logic model describing multilevel determinants of poor diet quality and guided prioritization of behavioural and environmental outcomes. An SCT-informed theory of change linking CHW-delivered strategies to key individual and household mechanisms, including nutrition literacy, self-efficacy, parental support, and food availability, was established. The adapted intervention comprised nine visual-aided nutrition education flyers tailored to rural Ugandan food environments and low-literacy audiences. Delivery was structured through CHW-led household sessions incorporating demonstrations, guided discussions, storytelling, myth correction, and persuasive communication. An evaluation plan was defined to assess implementation processes and effectiveness through a randomized controlled trial.</p> Conclusions <p>This study demonstrates a participatory, theory-driven approach to adapting nutrition interventions for rural AYAs. Aligning intervention content and delivery with existing community health systems offers a feasible and acceptable strategy to improve nutrition literacy and diet quality in rural Uganda and similar low-resource settings.</p>