Lacto-N-neodifucohexaose II (Compd 9), a derivative of a principal human milk tetrasaccharide [1], functions as a click chemistry reagent featuring an Azide group, enabling it to participate in copper-catalyzed azide-alkyne cycloaddition (CuAAc) with alkyne-bearing molecules and in strain-promoted alkyne-azide cycloaddition (SPAAC) with molecules containing DBCO or BCN groups.