In today’s cloud-driven environments, ensuring robust and sustainable application security is paramount. Amazon Web Services (AWS) Identity and Access Management (IAM) plays a crucial role in defining permissions and controlling access to critical cloud resources. However, overly permissive or misconfigured IAM policies often expose applications to significant security risks. This paper explores a comprehensive approach to enhancing sustainable application security by optimizing IAM policies and automating their management using AWS-native tools and best practices. We present methods to identify redundant or overly broad permissions, apply the principle of least privilege, and enforce policy compliance continuously. By integrating automation frameworks and leveraging AI/ML-based anomaly detection, this work demonstrates how to maintain a secure, auditable, and scalable IAM environment. The proposed strategy not only strengthens the security posture but also ensures operational efficiency and long-term sustainability of cloud applications.