AbstractA new approach exploiting the dual properties of thiol‐grafted cellulose paper for promoting copper‐catalyzed [3+2]‐cycloadditions of organic azides with alkynes and adsorbing residual copper species in solution was developed. The thiol‐grafted cellulose paper, used as a paper strip, effects the reduction of Cu^II to catalytically active Cu^I and acts as a powerful adsorbent for copper, thereby facilitating the work‐up process and leaving the crude mixture almost free of copper residues after a single filtration.