We have systematically investigated and found surprising superior catalytic activities of very short DNAzymes for copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC), both in solution and on surface. As a key reaction of the “click chemistry” class, CuAAC is a highly efficient and specific covalent conjugation tool with demonstrated applications in organic synthesis, bioconjugation, and surface functionalization; however, it requires the presence of the Cu(I) catalyst, which is an unstable species in aqueous solutions. We show here that one ultrashort, 14-nucleotide-truncated fragment of an earlier in vitroselected DNAzyme (CLICK-17) shows a striking and superior catalytic activity toward the in transCuAAC reaction in solution and on surface in the presence of either Cu(I) or Cu(II), at significantly lowered concentrations. These results obviate the need for long-sequence DNAzymes, selected out of the homogeneous solution phase, for application in complex surface environments.