The increasing use of mobile technologies in healthcare has driven significant advancements in patient care management while raising critical concerns about data security and privacy. This study addresses the challenges and solutions for ensuring security and privacy in mobile health applications, emphasizing the importance of integrating Privacy by Design (PbD) principles from the development phase. By implementing a framework in Flutter, the proposed approach focuses on safeguarding sensitive data through measures such as screenshot prevention and data encryption, ensuring strict compliance with regulations like the General Data Protection Law (LGPD). The results demonstrate that adopting PbD not only meets legal requirements but also strengthens user trust by effectively protecting personal data. The proposed framework establishes a new standard for developing mobile health applications, ensuring that security and privacy are integral throughout the entire design and operational process.