Zero-Trust Security Architecture (ZTSA) has emerged as a dominant paradigm in cybersecurity governance for modern organizations that rely on distributed systems, cloud platforms, and mobile technologies. Traditional perimeter-based security has proven insufficient in protecting enterprises against sophisticated cyber threats, insider attacks, data breaches, and supply-chain vulnerabilities. This paper develops a comprehensive conceptual model for Zero-Trust Governance (ZTG) by integrating organizational controls, identity management, risk monitoring, and compliance processes. A systematic review of existing frameworks—NIST 800-207, Forrester Zero Trust eXtended (ZTX), and industry standards—highlights the gaps in current governance practices. The proposed model provides a multilayered governance structure addressing identity, device, network, application, data, and operations governance. The research contributes a holistic theoretical framework that policymakers, CISOs, and digital transformation leaders can adopt to strengthen organizational cyber resilience.