CO2-Responsive polymer materials have received enormous attention in recent years, since CO2 as a new trigger has many advantages such as abundant availability, low cost, energy-saving, environment-friendly, non-toxic, good reversibility as well as great biocompatibility. In this review, we first discuss the virtues of CO2-responsiveness by comparing with traditional stimuli-sensitive materials that respond to pH, light, or redox stimuli. Then, the chemical fundamentals of CO2-responsive polymer materials are revealed including recently discovered ``unexpected{''} CO2-sensitive features. Recent progress of CO2-responsive polymer materials is highlighted followed by various CO2-responsive ``smart{''} polymer systems. Finally, challenges and outlooks in this area are discussed.