Healthy eating and sufficient physical activity is key for cardiometabolic health. A health-promoting environment makes a healthy lifestyle easier to adopt and maintain, and may be especially helpful to reach individuals with a lower socio-economic status (SES). In a paper just published in BMC Public Health we describe the Supreme Nudge project in which we will study the effects of pricing and nudging strategies in the supermarket – one of the most important point-of-choice settings for food choices – and of a context-specific mobile physical activity promotion app. Supreme Nudge uses a multi-disciplinary and mixed methods approach, integrating participatory action research, qualitative interviews, experimental pilot studies, and a randomized controlled trial in a real-life (supermarket) setting. First, we will identify the needs, characteristics and preferences of the target group as well as of the participating supermarket chain. Second, we will conduct a series of pilot studies to test novel, promising and feasible intervention components. Third, a final selection of intervention components will be implemented in a full-scale randomised controlled supermarket trial. Approximately 1000 adults with lower SES will be recruited across 8–12 supermarkets and randomised at supermarket level to receive 1) no intervention (control); 2) environmental nudges such as food product placement or promotion; 3) nudges and a tailored physical activity app that provides time- and context specific feedback; 4) pricing interventions, nudges, and the physical activity app. The effects on dietary behaviours, physical activity and cardiometabollic health will be evaluated. Additionally the Reach, Effectiveness, Adoption, Implementation and Maintenance (RE-AIM) of the intervention will be evaluated and insights from System Innovation and Transition Management theories will be used to define the best strategies for implementation and upscaling beyond the study period.