Functional impairment is a major problem for people with dementia. In most cases, family carers often provide care for functional disabilities without adequate knowledge and training. Smart-technologies are one means that may help family carers to improve their knowledge and training for functional disability care. This study aimed to develop an mHealth (smartphone) application for family carers of people with dementia to address their needs related to the management of functional disabilities of their care recipients. A mixed-method study was undertaken in Australia using an iterative co-design process consisting of two phases: (1) needs assessment, including an online survey and individual in-depth interviews with carers, and health and information technology [IT] experts; and (2) the development of content and prototype of an mHealth application. This study was informed by adult learning theory. The needs assessment phase aimed to identify family carers’ needs concerning the provision of functional disability care and use of mHealth applications when seeking health information. First, an exploratory, descriptive study was conducted through an online survey. Family carers of people with dementia living in the community with a diagnosis of any type and stage of dementia were recruited through dementia support websites and social media. In the survey, 166 family carers participated. The majority of family carers reported a moderate (54.2%) to high (37.3%) need for education concerning the provision of functional disability care. In the sample, 74.1% of respondents presented with a high level of carer burden, while 86.7% and 77% of respondents reported adequate health literacy and eHealth literacy levels. Almost all the respondents (98.8%) owned one or more smart-mobile devices. Just over half had experience using mHealth applications (51.2%). Approximately half the respondents (48.2%) stated that they had used mHealth applications to achieve health behaviour goals. The factors associated with the need for education about functional disability care were age, education and eHealth literacy level. The factors associated with having mHealth applications were employment status, eHealth literacy level and need for education about functional disability care. Following the survey, a qualitative descriptive exploratory study via in-depth interviews (in-person or by telephone) was undertaken. A purposive sample of family carers living in the community in Australia was recruited. Five child carers and five spousal carers participated. Four key themes were identified: (1) challenges that contribute to psychological distress and burden; (2) essential role of support systems in dementia care; (3) perception of information and educational needs among family carers, and (4) experiences and attitudes of mHealth applications as an educational and supportive resource. In the next stage, individual semi-structured interviews were conducted with experts following an interview guide. A convenience sample of experts who had experience with dementia care (two aged care nurses, two physicians, two occupational therapists) and an IT expert who had experience with mHealth application development participated in these interviews. Before conducting the interviews, a summary report based on the results of the online survey and individual interviews with carers, including areas proposed for the potential mHealth application, was distributed among the experts. All participants reported that managing needs related to functional disabilities were challenging for family carers. The experts claimed that barriers, challenges and difficulties that were highlighted by carers were common for family carers who provided care in the community. The experts agreed that the proposed content for the mHealth application was appropriate to address carers’ needs related to functional disability care. There was a concern, however, about the integration of a ‘chat room’ due to the need for continuous professional moderation, and this idea was, therefore, abandoned. In the co-design process, the triangulation of data from the needs assessment phase informed the content framework for the mHealth application. The application consists of three modules: (1) an overview of dementia and care, (2) managing daily living activities and (3) carers’ health and well-being. In addition to text information, currently available evidence-based online resources (websites, PDF articles and videos) were linked to the educational content. A nurse educator, an experienced geriatric nurse, a physician and two family carers reviewed the content. Readability of the content was checked based on the Flesch-Kincaid Readability Formula. Professional IT engineers developed an Android-based application using Java and Android Studio. Users can log into the application through a Google or Facebook login. The application was named the “Dementia Support for Carers app”. The application can be accessed through an Android-based smartphone or tablet. The co-design process helped to design and develop a new application for family carers based on the end user’s real-world experiences and the opinions and expertise of the stakeholders. However, before releasing this application into the App store, it is noted that testing of feasibility is essential. This thesis consists of seven chapters. Notably, chapters four to six present three published or submitted research articles reflecting the results of the online survey, interviews and the co-design process of the mHealth application, respectively. This dissertation does not include a traditional discussion chapter as each research article consists of a discussion of the results and the major findings of the study.