The rapid proliferation of cross-platform mobile applications has intensified the need for robust and scalable data security mechanisms, particularly within frameworks such as React Native. Despite its efficiency and flexibility, React Native introduces unique security challenges due to shared codebases, third-party dependencies, and platform abstraction layers. This study proposes an integrated architecture aimed at strengthening data security in cross-platform mobile applications developed using React Native. The research synthesizes existing approaches to mobile security, including anti-forensic techniques, secure API usage, and privacy-preserving mechanisms. A layered architectural model is introduced, incorporating encryption protocols, secure storage strategies, runtime protection, and privacy-preserving modules inspired by existing solutions such as SoProtector. The methodology employs a structured framework design supported by conceptual modeling and simulated validation scenarios. Findings indicate that integrating multi-layered security controls significantly reduces vulnerabilities associated with data leakage, reverse engineering, and unauthorized access. The proposed architecture offers a scalable, adaptable, and practical approach for developers and organizations aiming to enhance mobile application security. The study contributes to bridging gaps in existing literature by providing a unified and technically grounded solution tailored to cross-platform environments.