Electrolyte-free electrochemical glycosylation has been achieved using glycosyl acceptors equipped with an ionic-liquid tag as an intramolecular electrolyte and a separation tag. The one-pot electrolyte-free electrochemical glycosylation-Fmoc deprotection sequence enables rapid construction of oligosaccharides. The present method was successfully applied to the synthesis of a precursor of TMG-chitotriomycin.