Although numerous studies have focused on vehicle impacts with bridge piers, the effects of direct collisions on stay cables in cable-stayed bridges remain relatively underexplored. To address this gap, this study investigates the dynamic responses of stay cables under vehicular impact through a combination of scaled physical tests and numerical simulations. Inclined scaled cable specimens were tested to replicate realistic collision conditions, capturing dynamic responses such as impact force evolution, cable deformation, and localized damage. Test results indicated pronounced plastic deformation and slippage near the anchorage zones, but no complete cable failure was observed. A finite element model was developed and calibrated based on the experimental data, then extended to simulate vehicle-to-cable impacts on a representative bridge at various collision angles. The numerical results show that guardrails can reduce peak impact forces by up to 84.7% under small-angle impacts. However, as the collision angle increases, the guardrail’s redirection effectiveness is diminished, resulting in a higher probability of direct vehicle–cable contact and increased impact severity. The magnitude of impact force also rises notably with larger collision angles.