Background Mobile applications have the potential to assist patients and caregivers in managing chronic diseases, but current offerings are typically limited to a single disease or only focused on patients. A multifaceted app could expand the user base and provide more comprehensive support for patients who usually suffer from diverse chronic conditions at the same time and their caregivers. Objectives This study aimed to design, develop, and evaluate a mobile application that could aid chronic patients and their caregivers in managing the range of chronic conditions. Methods Focus group meetings were conducted with patients and caregivers to identify their needs, which were translated into app functionalities. The final version of the app was evaluated through a survey and analysis of the most used features. Results Five focus group (FG) meetings were held, involving 39 patients and 22 caregivers. The app included medication aids, self-monitoring aids, activation reminders, messages for caregiver shifts, remote monitoring, medicine management, and informative videos. Testing by 65 patients revealed that medication reminders (96.8% positive responses), medicine information (96.8%), messages for caregiver shifts (90.3%), and ease of use (80.6%) were the most valued aspects. The most frequently used feature was the health data record check. Conclusions A multifaceted mobile application can address the needs of a variety of chronic patients and their caregivers, while still being easy to use. The app's most used functionalities were aligned with the needs expressed in the FG, which reflects the success of this study and suggests that future research could benefit from incorporating similar user-centered design methodologies.