An N-heterocyclic carbene (NHC) polymer supported silver nanoparticle catalyst system was developed. The novel nano-composite catalyst demonstrated very high activity and excellent stability and reusability in the carboxylation of terminal alkynes with carbon dioxide at ambient conditions. The unique N-heterocyclic carbene polymer and silver nanoparticle composite structure provided a synergistic effect on activation of terminal alkynes and carbon dioxide that contributed to the high catalytic activity. The poly-NHC-silver catalyst exhibited excellent substrate generality and tolerance to various functionalities. In addition, the catalyst is stable to air and moisture and can be easily recovered and reused.