High-modulus polymers typically derive their properties from high crosslinking density and strong intermolecular interactions. In contrast, high-damping polymers primarily dissipate energy via the sliding and friction of mobile molecular segments. This fundamental contradiction creates an inherent trade-off, rendering the simultaneous achievement of high modulus and high damping a significant challenge. Herein, we report rigid-damping amphoteric ionic polymers (AIPs) developed through a cohesive entanglement strategy governed by side-chain ionic interactions. Synthesized via acid–base neutralization, these AIPs simultaneously achieve a high Young's modulus of 0.9 GPa and a damping coefficient (loss factor, tan δ) of up to 1.5. This breakthrough proposes a strategy to balance the modulus-damping trade-off and highlights the material's potential for advanced impact-resistant applications, such as transparent coatings for electronic devices and vibration-damping systems.