This thesis presents the design and implementation of a Secure Mobile Application Framework using Flutter, focused on integrating cybersecurity best practices into cross-platform development. The framework addresses key vulnerabilities identified in the OWASP Mobile Top 10, ensuring secure data storage, communication, and authentication. Comprehensive testing confirmed the framework’s effectiveness in enhancing app security without compromising performance. Overall, the thesis demonstrates a strong understanding of mobile cybersecurity and provides a practical foundation for developing secure, privacy-aware applications.