The growing complexity of modern banking systems has fundamentally reshaped the challenges of financial governance. Large-scale banks operate across multiple business lines, regulatory regimes, and technological platforms, creating governance environments in which traditional control-based oversight is increasingly insufficient. In such contexts, financial governance becomes not only a matter of compliance and assurance, but a core management challenge that directly affects decision quality, accountability, and systemic resilience. This article examines financial governance in complex banking systems from a management perspective grounded in internal audit leadership. It argues that internal audit leaders occupy a unique governance position that enables them to interpret, integrate, and evaluate financial decisionmaking across organizational boundaries. Rather than functioning solely as independent assurance providers, internal audit leaders contribute to financial governance by assessing how risk, control, and performance considerations are reconciled within managerial and board-level processes. Drawing on banking governance, finance management, and internal audit literature, the article develops a conceptual framework that positions internal audit leadership as a critical governance actor in complex systems. The analysis highlights how internal audit leaders translate governance expectations into managerial insight, support executive accountability, and enhance board-level oversight without assuming operational responsibility. Particular emphasis is placed on decision-making under complexity, systemic vulnerabilities, and the limitations of compliance-driven governance models. The article further explores organizational and regulatory constraints that shape the role of internal audit leadership in banking governance, noting the tensions between independence, integration, and managerial relevance. It concludes by outlining future directions for financial governance in complex banking systems, emphasizing the evolving contribution of internal audit leadership to sustainable and accountable financial management. By framing financial governance through the lens of internal audit leadership, this study advances the finance and banking governance literature and offers a management-oriented perspective on oversight in complex institutional environments.