Background: The progressive and complex nature of dementia demands carers have specific knowledge and training. However, often carers do not have adequate knowledge and skills, particularly for functional disability care. Aim: This study aims to develop and test the feasibility of an educational and supportive mHealth/smartphone application that addresses the needs of family carers of people with dementia related to functional disability of care recipients. Methods: This mixed method study consists of three phases. In phase one, an online survey and individual interviews with carers will be conducted to assess their needs related to management of functional disability and the development of an mHealth application. Additionally, experts will be consulted to identify their opinions on application development. In phase two, using information from phase one, an mHealth application will be designed and developed. In phase three, a feasibility study will be conducted with carers to identify usability, user adherence, acceptance and experiences with the application. Discussion: This study will generate new knowledge about the needs of carers related to the management of functional disability of people with dementia and the use of smartphones for health-seeking behaviours, and will develop an mHealth application for carers to address the needs related to functional disability care. Conclusion: A mixed method study was designed to develop a user-centred educational and supportive mHealth app for family carers to address needs related to the functional disability of people with dementia consisting of three phases: needs assessment, the designing of the app and a feasibility study