Lithium–oxygen batteries (LOBs) offer exceptionally high theoretical energy density by utilizing ambient oxygen as the cathodic reactant. However, practical performance is fundamentally constrained by sluggish oxygen reduction and evolution reactions arising from transport limitations within the air electrode. While extensive efforts have focused on catalyst development, the role of electrode microstructure in governing reactant distribution, triple-phase boundary (TPB) accessibility, and discharge-product evolution remains insufficiently understood. Here, we establish a microstructure–transport–performance framework by integrating digital twin–based structural analysis with one-dimensional (1D) electrochemical modeling. Architected three-dimensional (A3D) air electrodes with periodically defined unit cell geometries serve as model platforms to systematically decouple structural parameters. A physics-informed 1D model quantifies the interplay among specific surface area, porosity, and effective oxygen diffusivity in dictating oxygen flux, TPB stability, and discharge overpotential. The analysis reveals that microstructural regulation of oxygen transport directly governs reaction localization and capacity utilization. Guided by these mechanistic insights, we propose an improved A3D electrode design that minimizes transport polarization and enhances discharge capacity. This study demonstrates that rational microstructural programming beyond catalyst engineering provides a decisive pathway to stabilizing TPB dynamics in LOBs and related metal–air systems.