The corrosion-fatigue interaction is a highly complex, coupled chemical-mechanical degradation process that significantly affects the durability of critical reinforced concrete infrastructure exposed to combined corrosion and cyclic loading. Corrosion typically reduces structural integrity of reinforcement and induces cracks in the concrete, increasing stress concentrations and accelerating fatigue damage, while fatigue deterioration causes crack propagation in concrete, resulting in further exposure of the steel to aggressive agents and accelerating corrosion. This mutual interaction significantly shortens structural lifespan, underscoring the need for advanced modeling frameworks to improve lifetime prediction and support future digital twin concepts for structural health monitoring. This contribution presents a multiphysics phase-field modeling framework for simulating the corrosion-fatigue interaction in reinforced concrete. The framework models key physical processes: (i) chloride transport in concrete matrix leading to corrosion initiation, (ii) reactive transport and precipitation of Fe2+ and Fe3+ ions in the concrete pore space, (iii) pressure buildup around the steel reinforcement from precipitate accumulation (rust), (iv) corrosion diffusion in steel and its mechanical degradation, (v) fatigue degradation in steel reinforcement, (vi) fracture and fatigue crack propagation in concrete, and (vii) damage-dependent diffusivity in concrete, allowing the interaction between mechanically induced cracks and the corrosion process. These complex interacting processes are implemented within a coupled chemo-mechanical phase-field framework in FEniCS. Numerical examples in 2D and 3D illustrate the framework’s ability to capture the mutual interaction between corrosion and fatigue, highlighting how fatigue lifetime is influenced by corrosion state and how initial fatigue cracks can accelerate corrosion degradation process.