Fantasy sports applications represent a rapidly growing segment of the mobile application economy, yet their development for African football leagues remains significantly underdeveloped compared to European counterparts. This study documents the design, development, and evaluation of a fantasy football mobile application for the AZAM Premier League, Tanzania's top-flight football division, which also attracts substantial fan engagement from Uganda and the broader East African region. The application was developed using Flutter (Dart) for cross-platform deployment on Android and iOS, with a Firebase Realtime Database backend for live data synchronization. The development followed the Agile SDLC methodology across six two-week sprints. The application incorporates player selection, team management, live scoring, league creation, and social sharing features. System testing involved 85 beta users across three countries over eight weeks. Results indicate a mean user satisfaction score of 4.1 out of 5.0, an average session duration of 14.3 minutes, and a 30-day retention rate of 68%, comparing favorably with established fantasy sports benchmarks. Key findings reveal high demand for localized content, real-time match data integration, and social competition features. The study contributes a replicable development framework for fantasy sports applications targeting African football leagues.