This study presents an improved, dynamic input validation framework that marries client-side structural preprocessing with an integrated server-side middleware gateway layout to secure GraphQL-driven enterprise environments. Modern API ecosystems increasingly adopt GraphQL to replace rigid REST implementations; however, its structural flexibility introduces unique security hazards, payload validation complexities, and exposure to resource-exhaustion Denial-of-Service (DoS) vectors. Traditional server-side validation solutions often fail to inspect deep, multi-tiered relationships dynamically before the query hits core resolver code. By merging constructive and object-oriented design methodologies, we comparatively benchmarked this improved framework against standard GraphQL implementations across several operational conditions. Empirical results reveal that the proposed model yields a 40% reduction in error rates, a 40% optimization in network bandwidth usage, a 50% decrease in overall request parsing time, and a 30% elevation in total transaction throughput without degrading systemic data integrity. In alignment with the study's objectives, this research provides significant contributions to knowledge in the domain of GraphQL optimization by offering an adaptable and efficient input validation architecture capable of handling high-complexity queries while securing the system against injection attacks and data inconsistencies. The findings indicate that the proposed model not only strengthens system security but also enhances scalability and response times, proving its applicability to high-traffic environments. This research sets a foundation for future studies aimed at refining input validation strategies within evolving API technologies.