Abstract Background Effective integrated care interventions for hypertension (HT) and type 2 diabetes (T2D) exist and need to be scaled-up. The ‘SCale-Up diaBetes and hYpertension care' SCUBY project aims to facilitate scale-up of integrated care for HT and T2D through the implementation of contextualised scale-up roadmaps in Cambodia, Slovenia and Belgium and co-creation in policy dialogues. We herewith describe the plan for the process and scale-up evaluation of the SCUBY project, including the development, adoption and implementation of the roadmaps. The specific goals of the process evaluation are to (i) analyse how the reality of scale-up adheres to the developed roadmaps and (ii) assess how the different contexts can influence the implementation process of the scale-up strategies. Methods A comprehensive framework was developed to include context, process, scale-up and impact evaluation that is embedded in implementation and political theory. A diverse range of mostly qualitative tools - including a policy dialogue reporting form, a stakeholder follow-up interview and survey, project diaries and policy mapping - will be used to assess how stakeholders perceive the scale-up implementation process and adaptations to the roadmap. Key implementation outcomes include acceptability, feasibility relevance, adaptation, adoption and cost of roadmap activities. The role of context is relevant, and barriers and facilitators to scale-up will be continuously assessed. Conclusions The SCUBY project presents a comprehensive framework to guide the evaluation of scale-up of complex interventions. We describe three contextualised roadmaps, for Belgium, Slovenia and Cambodia, each adopting their own (horizontal/diversification/vertical) scale-up strategy(ies) as a basis to monitor adaptations through a co-creation process. This study protocol will be a guide for other scale-up interventions making use of knowledge translation and co-creation activities. Key messages Process evaluation is needed to keep track of complex interventions including scale up. The SCUBY project developed an evaluation plan to comprehensively monitor the scale-up of HT and T2D care.