Modern healthcare systems are increasingly challenged by fragmentation across clinical services, leading to delays, duplication, and variability in patient outcomes. Integrated clinical service pathways have emerged as a strategic approach to enhance coordination, streamline diagnostic processes, and strengthen emergency response across the full continuum of care. This comprehensive review synthesizes current evidence on system-level integration models that link early patient contact, clinical assessment, diagnostic decision-making, and definitive intervention within cohesive care pathways. Drawing on international literature, the review examines how structured coordination mechanisms, timely diagnostic integration, and responsive entry-point systems contribute to improved efficiency, patient safety, and clinical effectiveness. Key findings indicate that well-designed integrated pathways are associated with reduced response times, improved diagnostic accuracy, better continuity of care, and optimized resource utilization. Digital health infrastructures, interoperable information systems, and standardized governance frameworks are identified as critical enablers of successful integration. Despite these benefits, persistent challenges remain related to organizational silos, data fragmentation, and variability in implementation maturity. This review highlights best practices, identifies system-level gaps, and proposes an integrated conceptual perspective to support healthcare leaders and policymakers in advancing coordinated, high-performing healthcare systems.