A 3ʹ-Sialyl Lewis X tetrasaccharide (Neu5Acα2-3Galβ1-4[Fucα1-3]GlcNAc) equipped with an azide-functionalized linker through a short propyl spacer. The terminal azide can be covalently coupled to alkyne partners via copper-catalyzed azide-alkyne cycloaddition (CuAAC), or to dibenzocyclooctyne (DBCO) and related strained alkynes using copper-free click chemistry, forming stable 1,2,3-triazole linkages. 3ʹ-Sialyl Lewis X is the canonical carbohydrate ligand for the selectins (E-, P-, and L-selectin) and plays a central role in leukocyte rolling, cell adhesion, and inflammatory cascades. It is also a tumor-associated carbohydrate antigen relevant to cancer metastasis research. This probe can be used as a soluble inhibitor or immobilized on plates or sensors to investigate selectin binding, and it serves as a substrate for sialidases and fucosidases.