This case study details the implementation of a Zero Trust Architecture by a leading global financial institution to improve its security posture and adapt to regulatory demands. The organization faced challenges with traditional Role-Based Access Control (RBAC) and siloed systems, which were inadequate for modern security needs. To address these issues, the institution adopted Policy-Based Access Control (PBAC) to protect its extensive network and applications. The case study outlines how the PBAC approach facilitated dynamic authorization, reduced operational friction, and improved compliance and risk management. By centralizing access management, the organization was able to streamline policies across over 2,400 applications, enhancing security and governance. The implementation of PBAC not only strengthened the security framework but also led to operational efficiencies and cost savings by reducing manual processes. The results demonstrate the effectiveness of PBAC in supporting Zero Trust principles and ensuring scalable access management for future growth.