Studies have shown that foster children encounter many problems in everyday life. Three of these major problems are access to information, communication and integration. Studies have also shown that digital services such as mobile application can assist this particular type of user with their needs. However, when designing such a service, it is important that the right user experience design process which is suitable for the user will be implemented. For this reason, the goal of this study is to answer the following questions: “Which UX design guidelines are considered more efficient when designing a digital service, especially eHealth services, aimed for adolescent foster children?” In general, this study aims to identify which factors inside user experience design will lead to a more efficient experience for adolescent foster children from the age of 15 to 18. In order to accomplish this, the user centered design and design science research methodology were adopted for this study. Other methods such as literature study, interviews, usability test and heuristic evaluation test were also conducted. Furthermore, to evaluate the identified design guidelines, a mobile prototype which included the design guidelines were created. Based on the results from the usability test and heuristic evaluation test, it can be argued that the design features that would benefit adolescent foster children in a digital service are social features, accessing the right information at the right time, rewards and challenges. Other design features such positive color palates, clear navigation features and minimum use of instructional text should also be used. More importantly, when it came to understanding the needs of the focus group and the context specifics surrounding them, it was realized that designers should create trust with the user, including experts in the area, identifying ethical issues and the exact limitations that the focus group faces. It should be noted that at the beginning of this study, the main plan was to test the concept on actual foster children. Unfortunately, due to certain circumstances, this was not possible. Instead, a usability test and heuristic evaluation test for the prototype was conducted with participants that were experts in the areas related to this study.