A dual-functionalized nanoprobe was designed for highly sensitive and selective in situ evaluation of carbohydrates on living cells by integrating the specific carbohydrate recognition and enzymatic signal amplification of proteins on Au nanoparticles. A nanoscaffold of nanohorns functionalized with arginine-glycine-aspartic acid-serine tetrapeptide was also prepared on an electrode surface for cell capture and enhancing the electrical connectivity. Combined with the nanoprobe and peptide-nanohorns, a highly sensitive electrochemical strategy was developed for cytosensing, which showed a detection limit down to 15 cells, broad dynamic range, acceptable rapidity, and low cost. The proposed method was further used for monitoring of dynamic variation of carbohydrate expression on cancer cells in response to drugs, which obviated the destruction or labeling of cells and the covalent tagging of lectin and enzyme. The one-pot conjugation of three components was very convenient and could be extended for preparation of other lectin-functionalized nanoprobes. Further development of this technique would contribute considerably to meeting the challenges in comprehensive understanding of the glycomic codes.