This study aims to describe a protocol to develop a conceptual design for a technological device based on theoretical knowledge to improve medication adherence in people with dementia. The six steps of the intervention mapping approach will be systematically applied. Step 1 will be a needs assessment using a mixed-methods approach: a survey and interviews with carers to identify determinants of medication non-adherence. Device outcomes and objectives will be set in Step 2 followed by the selection of practical theory-informed methods in Step 3. In Step 4, the structure of the conceptual design will be determined through a Delphi technique. Finally, the implementation and evaluation plans for the design will be developed in Steps 5 and 6. To improve medication adherence in this population, the design should address the condition, patients’ and caregivers’ needs and factors contributing to the problem. Involvement of end-users and a multidisciplinary team will ensure a practical and fit-for-purpose design bridging the gap between research and practice.