Context: Mobile health (mHealth) provides an opportunity to use internet coverage in low- and middle-income countries to improve palliative care access and quality. Objectives: This study aimed to design a mobile phone application (app) to enable or improve communication between family caregivers, community caregivers, and palliative care teams; to evaluate its acceptability, processes, and mechanisms of action; and to propose refinements. Methods: A codesign process entailed collaboration between a Project Advisory Group and collaborators in India, Uganda, and Zimbabwe. We then trained community and family caregivers to use an app to communicate patient-reported outcomes to their palliative care providers each week on a data dashboard. App activity was monitored, and qualitative in-depth interviews explored experience with the app and its mechanisms and impact. Results N = 149 caregivers participated and uploaded n = 837 assessments of patient-reported outcomes. These data were displayed to the palliative care team on an outcomes dashboard on n = 355 occasions. Results: Qualitative data identified: 1) high acceptability and data usage; 2) improved understanding by team members of patient symptoms and concerns; 3) a need for better feedback to caregivers, for better prioritisation of patients according to need, for enhanced training and support to use the app, and for user-led recommendations for ongoing improvement. Conclusion: An outcomes-focused app and data dashboard are acceptable to caregivers and health-care professionals. They are beneficial in identifying, monitoring, and communicating patient outcomes and in allocating staff resource to those most in need.