An α-mannose-6-phosphate (Man6P) ligand equipped with a terminal alkyne through a hydrophilic PEG3 spacer. The alkyne couples to azide-functionalized partners via copper-catalyzed azide-alkyne cycloaddition (CuAAC), forming stable 1,2,3-triazole linkages. This compound enables the construction of lysosome-targeted therapeutics and research tools that exploit the mannose-6-phosphate receptor (M6PR), including applications in enzyme replacement therapy (ERT) for lysosomal storage disorders and in lysosome-targeting chimera (LYTAC) approaches for targeted protein degradation. The natural phosphate group provides authentic M6PR recognition, closely mimicking the endogenous Man6P glycan tag that directs newly synthesized lysosomal hydrolases to the lysosome.