An α2-6-sialylated tri-LacNAc oligosaccharide [Neu5Acα2-6(Galβ1-4GlcNAc)₃] equipped with an azide handle through a hydrophilic, discrete triethylene glycol (PEG3) spacer. The azide can be covalently coupled to alkynes via copper-catalyzed azide-alkyne cycloaddition (CuAAC) or to dibenzocyclooctyne (DBCO) and related strained alkynes via copper-free click chemistry, forming stable 1,2,3-triazole linkages. The α2-6-sialylated, multivalent poly-LacNAc presentation makes this a high-avidity ligand for Siglecs and for human-type influenza hemagglutinin, which preferentially recognizes α2-6-linked sialic acids. Used as a soluble inhibitor or as a click-conjugatable probe for surface-displayed Siglec and influenza receptor binding studies.