<p>While reinforced concrete (R/C) structures are favored for durability, reinforcement corrosion stands out as a critical factor that fundamentally undermines structural safety. This degradation is particularly alarming in seismically active regions, where corroded members can lead to premature failure. Despite these risks, current international standards, such as FEMA 356 and the Japanese Standard, rely heavily on empirical judgments rather than quantitative analytical procedures. To bridge this gap, this study integrates bond degradation into nonlinear finite element analysis (FEA) to evaluate the seismic resilience of corroded columns. The experimental program involved eight 0.6-scale specimens subjected to accelerated electrolytic corrosion and cyclic loading tests. The results demonstrate that flexural columns experience a sharp decline in yield and ultimate strength once the corrosion rate exceeds 10%, primarily due to the synergistic effects of reinforcement cross-sectional loss and bond-slip deterioration. Conversely, shear-dominated columns exhibit a linear reduction in load-bearing capacity as stirrup corrosion increases, leading to brittle failure modes while maintaining relatively stable ultimate displacement. To provide a comprehensive assessment, fifteen nonlinear FEA models were developed, incorporating a Gaussian-based bond-slip relationship. The FEA results showed excellent agreement with the experimental hysteretic responses up to a 35% corrosion rate. Notably, beyond 25% corrosion, the rapid deterioration of shear strength is further accelerated by severe bond loss. The established strength–deformation relationships at key structural states—cracking, yielding, and ultimate—provide a robust quantitative foundation for developing practical restoring force models. These findings facilitate more accurate seismic vulnerability assessments and effective rehabilitation strategies for aging R/C infrastructure.</p>