With the increasing demand for digital convenience, college merchandise stores often lack a dedicated mobile solution, making access to official products limited. This paper presents the design and development of a cross-platform mobile commerce application using Flutter to bridge this gap. The application provides an intuitive shopping experience by integrating secure payment gateways, real-time inventory updates, AI-powered recommendations, and seamless navigation. Built using Flutter and Firebase, the system ensures scalability, high performance, and security while maintaining a user-friendly interface. The Agile development approach was followed, allowing iterative improvements based on testing and feedback. Performance evaluation highlights improved operational efficiency, higher engagement rates, and increased accessibility for students, faculty, and alumni. This study showcases the effectiveness of Flutter for scalable mobile commerce applications and sets the groundwork for future enhancements, including AI-driven chatbots, AR-based virtual try-ons, and blockchain-secured transactions.