The covalent functionalization of metal oxide surfaces with organic ligands gives unique organic–inorganic hybrids. Here we report a bifunctional organic tether combining a phosphonate for metal oxide anchoring with an organic azide for attachment of organic groups. Stable binding of the tether to molecular and solid-state metal oxides is demonstrated and the subsequent “CLICKability” of the TiO₂-anchored tether is shown. The phosphonate-azide reported could in future allow the general linkage of functional organic groups to metal oxides.