Background: The integration of patient portals with electronic health records (EHRs) has been promoted globally to improve patient engagement, communication, and continuity of care. These platforms allow patients to access health information, schedule appointments, renew prescriptions, and communicate with providers. Challenges remain regarding usability, disparities in adoption, interoperability, and workflow integration. Objective: This study aimed to design and evaluate a patient portal system that functions as a comprehensive hub for patient-related data, addressing limitations identified in the literature regarding accessibility, interoperability, and patient engagement. Methods: We conducted a review of current evidence from international studies and systematic reviews focusing on EHR-integrated patient portals. The literature informed the portal’s design, with emphasis on interoperability, usability, equity of access, and integration into healthcare workflows. Key themes, patient experience, barriers to adoption, and provider perspectives were incorporated to guide system development. Results: Findings from the literature indicate that 90% of healthcare providers now offer portal access, only 15–30% of patients consistently use them without additional support. Usability testing demonstrates that positive experiences strongly correlate with higher engagement, while negative interactions reduce perceived value. Disparities in portal activation and use persist across age, socioeconomic status, and disease populations, with vulnerable groups less likely to benefit. Interoperability challenges, such as fragmented data formats, inconsistent access controls, and limited cross-institutional sharing, remain barriers to realizing the full potential of portals. Nonetheless, systematic reviews confirm that portals can improve health literacy, patient satisfaction, adherence, and some clinical outcomes, particularly in chronic disease management. Conclusion: Patient portals have the potential to transform patient engagement and healthcare delivery when designed with interoperability, usability, and equity in mind. Evidence highlights the importance of addressing disparities, integrating clinician workflows, and implementing robust governance frameworks for secure data exchange. The proposed system leverages these insights to create a comprehensive patient portal designed to enhance engagement, improve outcomes, and support continuity of care.