We synthesized yellow-emissive, fluorine-based conjugated polymer to fabricate CO2-responsive conjugated polymer nanoparticles (CPNPs). The CPNPs were functionalized with tertiary amine to have responsiveness to CO2. The amine-functionalized CPNPs became hydrophilic by CO2, bubbling because the bubbling led to formation of cationic ammonium ions at the side chains of the hydrophobic CPNPs. This resulted in high dispersion stability in aqueous phase even after vigorous mixing in the presence of organic phase (1-octanol). Subsequent N-2 bubbling was done to remove CO2 present in water, leading to deprotonation of the side chains of CPNPs. The CPNPs became hydrophobic and moved to the organic phase. The CO2-responsive property was based on the amine groups in the side chain of polymer that reversibly interacted with bicarbonate ion (HCO3-), formed by dissolving CO2 in water, generating switchable hydrophilicity and hydrophobicity.