During national, regional, and local catastrophes, reliable public alert and warning systems are critical for saving lives and protecting property. Emergency notifications have become a top issue in both national and local governments these days. Makati City Government aspires to be the Philippines' most livable City, which implies it will be renowned for good education, good healthcare, and a decent environment. Disaster risk reduction and climate change adaptation must be substantial to attain this aim of shared socioeconomic growth. This research focuses on designing and developing a Mamamayan: An Android mobile Community-based Emergency Reporting and Notification System. It is a mobile-based, resiliency-based emergency alert notification system that informs concerned individuals of any crises, accidents, or problems that demand prompt attention from the local government sector. Featured-driven development (FDD) in Agile methodology was employed to bring this project to life. Related perspectives from all walks of life were considered to seek social awareness, readiness to respond, and willingness to utilize a mobile app to report an occurrence of an emergency. This application cleared the path for a better agency response and levering individuals to utilize IT solutions to become resilient in emergencies, with 95% of respondents eager to report accidents or emergencies. Mamamayan can be used to report emergencies ranging from fires to typhoon-related incidents, vehicular accidents with casualties, emergency health-related concerns, community-related incidents and concerns, and other occurrences that require an immediate and concrete response from the responsible agencies. The geolocation capabilities of smartphones are integrated into the application to allow the dispatcher to locate the caller's exact location. A robust emergency alarm communication system like Mamamayan is vital for a densely populated metropolis like Makati City. The IBM's Post-Study System Usability Questionnaire (PSSUQ) and the ISO 9126 were used to evaluate the proposed system yielding a high acceptance as perceived satisfaction from the evaluators. The PSSUQ usability test resulted in a 1.50 overall mean, indicating that the system was highly acceptable in terms of system usefulness, information quality, interface quality, and overall satisfaction. The system effectively captured respondents' perceptions of satisfaction, as evidenced by an overall mean of 4.71 (highly acceptable) on the ISO/IEC 9126 software quality test. The evaluation took into account system performance, reliability and availability, efficiency, maintainability, and portability.